text:
Pagina principale Nurse's Manual of Laboratory and Diagnostic Tests 4th Edition
Nurse's Manual of Laboratory and Diagnostic Tests 4th EditionBonita Morrow Cavanaugh
Covering 25 categories of tests, this guide presents information to enhance patient care planning and implementation. For each type of test, information is provided on anatomic, physiological, and pathophysiological understandings of procedures; reference values, including variations related to age
Leggi il libro online
You can write a book review and share your experiences. Other readers will always be interested in your opinion of the books you've read. Whether you've loved the book or not, if you give your honest and detailed thoughts then people will find new books that are right for them.
Copyright © 2003 F.A. Davis Company Nurse's Manual of Laboratory and Diagnostic Tests EDITION Bonita Morrow Cavanaugh, PhD, RN Clinical Nurse Specialist Nursing Education The Children's Hospital Denver, Colorado Clinical Faculty University of Colorado Health Sciences Center School of Nursing Denver, Colorado Affiliate Professor University of Northern Colorado School of Nursing Greeley, Colorado F.A. Davis Company • Philadelphia Copyright © 2003 F.A. Davis Company F. A. Davis Company 1915 Arch Street Philadelphia, PA 19103 www.fadavis.com Copyright © 2003 by F. A. Davis Company Copyright © 1999, 1995, 1989 by F. A. Davis Company. All rights reserved. This book is protected by copyright. No part of it may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without written permission from the publisher. Printed in the United States of America Last digit indicates print number: 10 9 8 7 6 5 4 3 2 1 Publisher: Lisa Deitch Developmental Editor: Diane Blodgett Cover Designer: Louis J. Forgione As new scientific information becomes available through basic and clinical research, recommended treatments and drug therapies undergo changes. The author and publisher have done everything possible to make this book accurate, up to date, and in accord with accepted standards at the time of publication. The author, editors, and publisher are not responsible for errors or omissions or for consequences from application of the book, and make no warranty, expressed or implied, in regard to the contents of the book. Any practice described in this book should be applied by the reader in accordance with professional standards of care used in regard to the unique circumstances that may apply in each situation. The reader is advised always to check product information (package inserts) for changes and new information regarding dose and contraindications before administering any drug. Caution is especially urged when using new or infrequently ordered drugs. Library of Congress Cataloging-in-Publication Data Cavanaugh, Bonita Morrow, 1952– Nurse's manual of laboratory and diagnostic tests. – 4th ed. / Bonita Morrow Cavanaugh. p. cm. Rev. ed. of: Nurse's manual of laboratory and diagnostic tests / Juanita Watson. 3rd. ed. c1995. Includes bibliographical references and index. ISBN 0-8036-1055-6 (pbk.) 1. Diagnosis, Laboratory —Handbooks, manuals, etc. 2. Nursing-Handbook, manuals, etc. I. Watson, Juanita, 1946– Nurse's manual of laboratory and diagnostic tests. II. Title. [DNLM: 1. Laboratory Techniques and Procedures nurses' instruction handbooks. QY 39 C377n 1999] RT48.5.W38 1999 616.07′5—dc21 DNLM/DLC for Library of Congress 98-50920 CIP Authorization to photocopy items for internal or personal use, or the internal or personal use of specific clients, is granted by F. A. Davis Company for users registered with the Copyright Clearance Center (CCC) Transactional Reporting Service, provided that the fee of $.10 per copy is paid directly to CCC, 222 Rosewood Drive, Danvers, MA 01923. For those organizations that have been granted a photocopy license by CCC, a separate system of payment has been arranged. The fee code for users of the Transactional Reporting Service is: 8036-1055/03 0 + $.10. Copyright © 2003 F.A. Davis Company To Laurie O'Neil Good, the finest nurse I have ever known. Love, Bonnie Copyright © 2003 F.A. Davis Company This page intentionally left blank Copyright © 2003 F.A. Davis Company Preface This book is designed to provide both students and practitioners of nursing with the information they need to care for individuals undergoing laboratory and diagnostic tests and procedures. The content is presented as a guiding reference for planning care, providing specific interventions, and evaluating outcomes of nursing care. In this edition, the background information and description of the test or procedure are followed directly by the clinical applications data, starting with reference values, for each test or group of tests. The introductory sections include the anatomic, physiological, and pathophysiological content necessary for a thorough understanding of the purpose of and indications for specific tests and procedures. The inclusion of this information makes this book unlike many other references on this subject matter. This feature enhances the integration of basic science knowledge with an understanding of and application to diagnostic testing. This is extremely helpful for nursing students in developing critical thinking and clinical judgment. For each test or study within the respective sections, reference values, including variations related to age or gender, are provided. Critical values, where appropriate, are highlighted. Both conventional units and international units are provided. Readers are encouraged to be aware of some variation in laboratory values from agency to agency. For all tests, interfering factors are noted where appropriate. Contraindications and Nursing Alerts are included to provide information crucial to safe and reliable testing and nursing care. Other features of this manual that contribute to its practical use are presentation of detailed content in tabular format when appropriate and the use of appendices to provide essential information applicable to most, if not all, tests and procedures. Every effort has been made to include tests and procedures currently in use in practice settings. It is recognized that newer tests and procedures may have become available after this manuscript was prepared. Readers are encouraged to keep abreast of current literature and consult with laboratories and agencies in their area for new developments in the field of diagnostic tests. BONITA MORROW CAVANAUGH v Copyright © 2003 F.A. Davis Company This page intentionally left blank Copyright © 2003 F.A. Davis Company Acknowledgments This book would not have been possible without the help, support, and encouragement of a number of people. Special appreciation is due to the staff of the F. A. Davis Company. I am particularly indebted to Lisa Deitch, Publisher, for her major contribution in developing the unique format of this text, for her encouragement, and for always being available for help when I needed it. I would also like to acknowledge Robert Martone, Nursing Publisher, who encouraged me to pursue this project, and Robert H. Craven, Jr., President, for his support and patience as the book evolved. Special thanks are also due to Ruth De George, Editorial Assistant, and Michele Reese, Editorial Aide, for their invaluable assistance. Many other individuals at the F. A. Davis Company contributed to the production of this book, and I wish to extend to all of them my sincere appreciation for their expertise and dedication to the high standards necessary to produce a good book. Special recognition in this regard is due to Jessica Howie Martin, Production Editor, and Bob Butler, Director of Production. I thank the consultants who served as reviewers of the manuscript for their thoroughness and generosity in sharing their ideas and suggestions. Your comments proved invaluable! Finally, a special thanks to those family members, friends, and associates who offered and gave their support, patience, and encouragement. B.M.C. vii Copyright © 2003 F.A. Davis Company This page intentionally left blank Copyright © 2003 F.A. Davis Company Consultants Janice Brownlee, BScN, MAEd Dolores Philpot, BSMT, AND, MSN Professor Canadore College of Applied Arts and Technology North Bay, Ontario, Canada Instructor University of Tennessee Knoxville, Tennessee Sylvan L. Settle, RN Marie Colucci, BS, MS, EdD Associate Professor Riverside Community College Riverside, California Vocational Teacher Tennessee Technology Center Memphis, Tennessee Joyce Taylor, RN, MSN, DSN, BA Mary Jo Goolsby, MSN, ARNP, EdD Instructor Florida State University Tallahassee, Florida Associate Professor Henderson State University Arkadelphia, Arkansas Shelley M. Tiffin, ART (CSMLS), BMLSc Shelby Hawk, RN, MSN Instructor Mid Michigan Community College Harrison, Michigan Priscilla Innocent, RN, MSN Associate Professor Indiana Wesleyan University Marion, Indiana Dr. Fran Keen, RN, DNSc Bachelor of Medical Laboratory Science Program Department of Pathology and Laboratory Medicine University of British Columbia Vancouver, British Columbia, Canada Donna Yancey, BSN, MSN, DNS Assistant Professor Purdue University West Lafayette, Indiana Associate Professor University of Miami Coral Gables, Florida ix Copyright © 2003 F.A. Davis Company This page intentionally left blank Copyright © 2003 F.A. Davis Company Contents SECTION I • Laboratory Tests, 1 CHAPTER 1 Hematology and Tests of Hematopoietic Function ......................................................................3 CHAPTER 2 Hemostasis and Tests of Hemostatic Functions ........................................................................39 CHAPTER 3 Immunology and Immunologic Testing ........................................................................................60 CHAPTER 4 Immunohematology and Blood Banking......................................................................................96 CHAPTER 5 Blood Chemistry..............................................................................................................................103 CHAPTER 6 Studies of Urine ..............................................................................................................................221 CHAPTER 7 Sputum Analysis ............................................................................................................................268 CHAPTER 8 Cerebrospinal Fluid Analysis ......................................................................................................274 CHAPTER 9 Analysis of Effusions ....................................................................................................................283 CHAPTER 10 Amniotic Fluid Analysis ................................................................................................................297 CHAPTER 11 Semen Analysis ..............................................................................................................................305 CHAPTER 12 Analysis of Gastric and Duodenal Secretions..........................................................................311 xi Copyright © 2003 F.A. Davis Company xii Contents CHAPTER 13 Fecal Analysis ................................................................................................................................321 CHAPTER 14 Analysis of Cells and Tissues ......................................................................................................332 CHAPTER 15 Culture and Sensitivity Tests........................................................................................................352 SECTION II • Diagnostic Tests and Procedures, 361 CHAPTER 16 Endoscopic Studies........................................................................................................................363 CHAPTER 17 Radiologic Studies ........................................................................................................................397 CHAPTER 18 Radiologic Angiography Studies ................................................................................................438 CHAPTER 19 Ultrasound Studies ........................................................................................................................458 CHAPTER 20 Nuclear Scan and Laboratory Studies ......................................................................................482 CHAPTER 21 Non-Nuclear Scan Studies ..........................................................................................................528 CHAPTER 22 Manometric Studies ......................................................................................................................545 CHAPTER 23 Electrophysiologic Studies ..........................................................................................................558 CHAPTER 24 Studies of Specific Organs or Systems......................................................................................577 CHAPTER 25 Skin Tests ........................................................................................................................................615 APPENDICES APPENDIX I Obtaining Various Types of Blood Specimens..........................................................................625 APPENDIX II Obtaining Various Types of Urine Specimens ..........................................................................631 APPENDIX III Guidelines for Isolation Precautions in Hospitals ..................................................................634 APPENDIX IV Units of Measurement (Including SI Units) ..............................................................................636 Copyright © 2003 F.A. Davis Company Contents APPENDIX V Profile or Panel Groupings and Laboratory Tests ....................................................................644 APPENDIX VI Nursing Care Plan for Individuals Experiencing Laboratory and Diagnostic Testing ............................................................................................649 INDEX ..............................................................................................................................................651 xiii Copyright © 2003 F.A. Davis Company This page intentionally left blank Copyright © 2003 F.A. Davis Company SECTION Laboratory Tests 1 Copyright © 2003 F.A. Davis Company This page intentionally left blank Copyright © 2003 F.A. Davis Company CHAPTER Hematology and Tests of Hematopoietic Function TESTS COVERED Bone Marrow Examination, 7 Reticulocyte Count, 9 Iron Studies, 11 Vitamin B12 and Folic Acid Studies, 13 Complete Blood Count, 14 Erythrocyte (RBC) Count, 20 Hematocrit, 21 Hemoglobin, 21 Red Blood Cell Indices, 22 Stained Red Blood Cell Examination, 24 Hemoglobin Electrophoresis, 26 Osmotic Fragility, 29 Red Blood Cell Enzymes, 30 Erythrocyte Sedimentation Rate, 31 White Blood Cell Count, 33 Differential White Blood Cell Count, 34 White Blood Cell Enzymes, 37 INTRODUCTION Blood constitutes 6 to 8 percent of total body weight. In terms of volume, women have 4.5 to 5.5 L of blood and men 5 to 6 L. In infants and children, blood volume is 50 to 75 mL/kg in girls and 52 to 83 mL/kg in boys. The principal functions of blood are the transport of oxygen, nutrients, and hormones to all tissues and the removal of metabolic wastes to the organs of excretion. Additional functions of blood are (1) regulation of temperature by transfer of heat to the skin for dissipation by radiation and convection, (2) regulation of the pH of body fluids through the buffer systems and facilitation of excretion of acids and bases, and (3) defense against infection by transportation of antibodies and other substances as needed. Blood consists of a fluid portion, called plasma, and a solid portion that includes red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes). Plasma makes up 45 to 60 percent of blood volume and is composed of water (90 percent), amino acids, proteins, carbohydrates, lipids, vitamins, hormones, electrolytes, and cellular wastes.1 Of the "solid" or cellular portion of the blood, more than 99 percent consists of red blood cells. Leukocytes and thrombocytes, although functionally essential, occupy a relatively small portion of the total blood cell mass.2 Erythrocytes remain within the blood throughout their normal life span of 120 days, transporting oxygen in the hemoglobin component and carrying away carbon dioxide. Leukocytes, while they are in the blood, are merely in transit, because they perform their functions in body tissue. Platelets exert their effects at the walls of blood vessels, performing no known function in the bloodstream itself.3 Hematology is traditionally limited to the study of the cellular elements of the blood, the production of these elements, and the physiological derangements that affect their functions. Hematologists also are concerned with blood volume, the flow properties of blood, and the physical relationships of red cells and plasma. The numerous substances dissolved or suspended in plasma fall within the province of other laboratory disciplines.4 3 Copyright © 2003 F.A. Davis Company 4 SECTION I—Laboratory Tests HEMATOPOIESIS Hematopoiesis is the process of blood cell formation. In normal, healthy adults, blood cells are manufactured in the red marrow of relatively few bones, notably the sternum, ribs, vertebral bodies, pelvic bones, and proximal portions of the humerus and the femur. This production is in contrast to that taking place in the embryo, in which blood cells are derived from the yolk sac mesenchyme. As the fetus develops, the liver, the spleen, and the marrow cavities of nearly all bones become active hematopoietic sites (Fig. 1–1). In the newborn, hematopoiesis occurs primarily in the red marrow, which is found in most bones at that stage of development. Beginning at about age 5 years, the red marrow is gradually replaced by yellowish fat-storage cells (yellow marrow), which are inactive in the hematopoietic process. By adulthood, blood cell production normally occurs in only those bones that retain red marrow activity.5 Adult reticuloendothelial cells retain the potential for hematopoiesis, although in the healthy state reserve sites are not activated. Under conditions of hematopoietic stress in later life, the liver, the spleen, and an expanded bone marrow may resume the production of blood cells. All blood cells are believed to be derived from the pluripotential stem cell,6 an immature cell with the capability of becoming an erythrocyte, a leukocyte, or a thrombocyte. In the adult, stem cells in hematopoietic sites undergo a series of divisions and maturational changes to form the mature cells found in the blood (Fig. 1–2). As they achieve the "blast" stage, stem cells are committed to becoming a specific type of blood cell. This theory also explains the origin of the several types of white blood cells (neutrophils, monocytes, eosinophils, basophils, and lymphocytes). As the cells mature, they lose their ability to reproduce and cannot further divide to replace themselves. Thus, there is a need for continuous hematopoietic activity to replenish worn-out or damaged blood cells. Erythropoiesis, the production of red blood cells (RBCs), and leukopoiesis, the production of white blood cells (WBCs), are components of the hematopoietic process. Erythropoiesis maintains a population of approximately 25 1012 circulating RBCs, or an average of 5 million erythrocytes per cubic millimeter of blood. The production rate is about 2 million cells per second, or 35 trillion cells per day. With maximum stimulation, this rate can be increased sixfold to eightfold, or one volume per day equivalent to the cells contained in 0.5 pt of whole blood. The level of tissue oxygenation regulates the production of RBCs; that is, erythropoiesis occurs in response to tissue hypoxia. Hypoxia does not, Figure 1–1. Location of active marrow growth in the fetus and adult. (From Hillman, RS, and Finch, CA: Red Cell Manual, ed 7. FA Davis, Philadelphia, 1996, p 2, with permission.) Copyright © 2003 F.A. Davis Company CHAPTER 1—Hematology and Tests of Hematopoietic Function 5 Image/Text rights unavailable however, directly stimulate the bone marrow. Instead, RBC production occurs in response to erythropoietin, precursors of which are found primarily in the kidney and to a lesser extent in the liver. When the renal oxygen level falls, an enzyme, renal erythropoietic factor, is secreted. This enzyme reacts with a plasma protein to form erythropoietin, which subsequently stimulates the bone marrow to produce more RBCs. Specifically, erythropoietin (1) accelerates production, differentiation, and maturaTABLE 1–1 • tion of erythrocytes; (2) reduces the time required for cells to enter the circulation, thereby increasing the number of circulating immature erythrocytes such as reticulocytes (see Fig. 1–2); and (3) facilitates the incorporation of iron into RBCs. When the number of produced erythrocytes meets the body's tissue oxygenation needs, erythropoietin release and RBC production are reduced. Table 1–1 lists causes of tissue hypoxia that may stimulate the release of erythropoietin. Causes of Tissue Hypoxia That May Stimulate Erythropoietin Release Acute blood loss Impaired oxygen–carbon dioxide exchange in the lungs Low hemoglobin levels Impaired binding of oxygen to hemoglobin Impaired release of oxygen from hemoglobin Excessive hemolysis of erythrocytes due to hypersplenism or hemolytic disorders of antibody, bacterial, or chemical origin Certain anemias in which abnormal red blood cells are produced (e.g., hereditary spherocytosis) Compromised blood flow to the kidneys Copyright © 2003 F.A. Davis Company 6 SECTION I—Laboratory Tests Threats to normal erythropoiesis occur if sufficient amounts of erythropoietin cannot be produced or if the bone marrow is unable to respond to erythropoietic stimulation. People without kidneys or with severe impairment of renal function are unable to produce adequate amounts of renal erythropoietic factor. In these individuals, the liver is the source of erythropoietic factor. The quantity produced, however, is sufficient to maintain only a fairly stable state of severe anemia that responds minimally to hypoxemia. Inadequate erythropoiesis may occur also if the bone marrow is depressed because of drugs, toxic chemicals, ionizing radiation, malignancies, or other disorders such as hypothyroidism. Also, in certain anemias and hemoglobinopathies, the bone marrow is unable to produce sufficient normal erythrocytes. Other substances needed for erythropoiesis are vitamin B12, folic acid, and iron. Vitamin B12 and TABLE 1–2 • folic acid are required for DNA synthesis and are needed by all cells for growth and reproduction; because cellular reproduction occurs at such a high rate in erythropoietic tissue, formation of RBCs is particularly affected by a deficiency of either of these substances. Iron is needed for hemoglobin synthesis and normal RBC production. In addition to dietary sources, iron from worn-out or damaged RBCs is available for reuse in erythropoiesis.7 Leukopoiesis, the production of WBCs, maintains a population of 5,000 to 10,000 leukocytes per cubic millimeter of blood, with the capability for rapid and dramatic change in response to a variety of stimuli. No leukopoietic substance comparable to erythropoietic factor has been identified, but many factors are known to influence WBC production, with a resultant excess (leukocytosis) or deficiency (leukopenia) in leukocytes (Table 1–2). Note that WBC levels vary in relation to diurnal Causes of Altered Leukopoiesis Physiological Leukocytosis Pathological Pregnancy All types of infection Early infancy Anemias Emotional stress Cushing's disease Strenuous exercise Erythroblastosis fetalis Menstruation Leukemias Exposure to cold Polycythemia vera Ultraviolet light Transfusion reactions Increased epinephrine secretion Inflammatory disorders Parasitic infestations Leukopenia Diurnal rhythms Bone marrow depression Toxic and antineoplastic drugs Radiation Severe infection Viral infections Myxedema Lupus erythematosus and other autoimmune disorders Peptic ulcers Uremia Allergies Malignancies Metabolic disorders Malnutrition Copyright © 2003 F.A. Davis Company CHAPTER 1—Hematology rhythms; thus, the time at which the sample is obtained may influence the results. Overall, leukocytes may increase by as many as 2000 cells per milliliter from morning to evening, with a corresponding overnight decrease. Eosinophils decrease until about noon and then rise to peak between midnight and 3 AM. This variation may be related to adrenocortical hormone levels, which peak between 4 and 8 AM, because an increase in these hormones can cause circulating lymphocytes and eosinophils to disappear in a few hours. Evaluation of Hematopoiesis Abnormal results of studies such as a complete blood count (CBC)) and WBC count and differential indicate the need to determine the individual's hematopoietic function. Evaluation of hematopoiesis begins with the examination of a bone marrow sample and may subsequently require other studies and a sample of peripheral blood, either venous or capillary. Although the collection of blood specimens is usually the responsibility of the laboratory technician or phlebotomist, it is often the responsibility of the nurse in emergency departments, critical TABLE 1–3 Cell Type Reticulocytes Neutrophils (total) • and Tests of Hematopoietic Function care units, and community and home care settings. A detailed description of procedures for obtaining peripheral blood samples is provided in Appendix I. BONE MARROW EXAMINATION Bone marrow examination (aspiration, biopsy) requires removal of a small sample of bone marrow by aspiration, needle biopsy, or open surgical biopsy. Cells normally present in hematopoietic marrow include erythrocytes and granulocytes (neutrophils, basophils, and eosinophils) in all stages of maturation; megakaryocytes (from which platelets develop); small numbers of lymphocytes; and occasional plasma cells (Fig. 1–2). Nucleated WBCs in the bone marrow normally outnumber nucleated (immature) RBCs by about 3:1. This is called the myeloid-to-erythroid (M:E) ratio.8 Causes of increased and decreased values on bone marrow examination are presented in Table 1–3. Various stains followed by microscopic examination can be performed on bone marrow aspirate to diagnose and differentiate among the different types of leukemia. A Sudan B stain differentiates between acute granulocytic and lymphocytic Causes of Alterations in Bone Marrow Cells Increased Values Decreased Values Compensated RBC loss Aplastic crisis of sickle cell disease or hereditary spherocytosis Response to vitamin B12 therapy Aplastic anemia Myeloid (chronic) leukemias Leukemias (monocytic and lymphoblastic) Acute myeloblastic leukemia Lymphocytes Lymphatic leukemia Lymphosarcoma Lymphomas Mononucleosis Aplastic anemia Plasma cells Myeloma Normoblasts Polycythemia vera Deficiency of folic acid or vitamin B12 Aplastic anemia Hemolytic anemia Eosinophils 7 Bone marrow carcinoma Lymphadenoma Myeloid leukemia Copyright © 2003 F.A. Davis Company 8 SECTION I—Laboratory Tests leukemia. A periodic acid–Schiff stain assists in the diagnosis of acute lymphocytic leukemia and erythroleukemia. A terminal deoxynucleotidyl transferase test differentiates between lymphoblastic leukemia and lymphoma.9 Because bone marrow examination involves an invasive procedure with risks of infection, trauma, and bleeding, a signed consent is required. INDICATIONS FOR BONE MARROW EXAMINATION Evaluation of abnormal results of CBC (e.g., anemia), of WBC count with differential (e.g., increased numbers of leukocyte precursors), or of both tests Monitoring of effects of exposure to bone marrow depressants Monitoring of bone marrow response to antineoplastic or radiation therapy for malignancies Evaluation of hepatomegaly (enlarged liver) or splenomegaly (enlarged spleen) Identification of bone marrow hyperplasia or hypoplasia, although the study may not indicate the cause of the quantitative abnormality Determination of marrow differential (proportion of the various types of cells present in the marrow) and M:E ratio Diagnosis of various disorders associated with abnormal hematopoiesis: Multiple myeloma Most leukemias, both acute and chronic Disseminated infections (granulomatous, bacterial, fungal) Lipid or glycogen storage diseases Reference Values Cell Type (%) Adults Infants Children 0–1.0 — — 0.5–2.5 — — 56.5 32.4 57.1 Myeloblasts 0.3–5.0 0.62 1.2 Promyelocytes 1.4–8.0 0.76 1.4 Myelocytes 4.2–15.0 2.5 18.4 Neutrophilic 5.0–19.0 — — Eosinophilic 0.5–3.0 — — 0–0.5 — — Bands (stabs) 13.0–34.0 14.1 0 Lymphocytes 14.0–16.0 49.0 16.0 Monocytes 0.3–6.0 — — Plasma cells 0.3–3.9 0.02 0.4 Megakaryocytes 0.1–3.0 0.05 0.1 2.3–3.5:1 4.4:1 2.9:1 0.2–1.3 0.1 0.5 25.6 8.0 23.1 Basophilic 1.4–4.0 0.34 1.7 Polychromatophilic 6.0–29.0 6.9 18.2 Orthochromic 1.0–4.6 0.54 2.7 Eosinophils 0.5–3.0 2.6 3.6 0–0.2 0.07 0.06 Undifferentiated Reticulocytes Neutrophils (total) Basophilic M:E ratio Pronormoblasts Normoblasts Basophils Note: There may be differences in normal values among individuals and in values obtained by different laboratory techniques. Copyright © 2003 F.A. Davis Company CHAPTER 1—Hematology Hypoplastic anemia (which may be caused by chronic infection, hypothyroidism, chronic renal failure, advanced liver disease, and a number of "idiopathic" conditions) Erythropoietic hyperplasia (which may be caused by iron deficiency, thalassemias, hemoglobinopathies, disorders of folate and vitamin B12 metabolism, hypersplenism, glucose-6phosphate dehydrogenase [G-6-PD] deficiency, hereditary spherocytosis, and antibody-mediated bacterial or chemical hemolysis) Lupus erythematosus Porphyria erythropoietica Parasitic infestations Amyloidosis Polycythemia vera Aplastic anemia (which may be caused by drug toxicity, idiopathic marrow failure, or infection) CONTRAINDICATIONS Known coagulation defects, although the test may be performed if the importance of the information to be obtained outweighs the risks involved in carrying out the test NURSING CARE BEFORE THE PROCEDURE Explain to the client: The purpose of the study That it will be done at the bedside by a physician and requires about 20 minutes The general procedure, including the sensations to be expected (momentary pain as the skin is injected with local anesthetic and again as the needle penetrates the periosteum, the "pulling" sensation as the specimen is withdrawn) That discomfort will be minimized with local anesthetics or systemic analgesics That the site may remain tender for several weeks Ensure that a signed consent has been obtained. Then: Take and record vital signs. Provide a hospital gown if necessary to provide access to the biopsy site or to prevent soiling of the client's clothes with the solution used for skin preparation. Administer premedication prescribed for pain or anxiety. and Tests of Hematopoietic Function 9 preferred. In adults, the sternum or iliac crests are the preferred sites. The prone or side-lying position is used if the spinous processes are the sites to be used. (These sites are preferred if more than one specimen is to be obtained.) The client may also be sitting, supported by a pillow on an overbed table for a spinous process site. The side-lying position is used if the iliac crest or tibia is the site. For sternal punctures, the supine position is used. The skin is prepared with an antiseptic solution, draped, and anesthetized, preferably with procaine, which is painless when injected. Asepsis must be meticulous to prevent systemic infection. For aspiration, a large needle with stylet is advanced into the marrow cavity. Penetration of the periosteum is painful. The stylet is removed and a syringe is attached to the needle. An aliquot of 0.5 mL of marrow is withdrawn. At this time, the discomfort is a "pulling" sensation rather than pain. The needle is removed and pressure applied to the site. The aspirate is immediately smeared on slides and, when dry, sprayed with a fixative. For needle biopsy, the local anesthetic is introduced deeply enough to include the periosteum. A special cutting biopsy needle is introduced through a small skin incision and bored into the marrow cavity. A core needle is introduced through the cutting needle and a plug of marrow is removed. The needles are withdrawn and the specimen placed in a preservative solution. Pressure is applied to the site for 5 to 10 minutes and a dressing applied. NURSING CARE AFTER THE PROCEDURE Care and assessment after the procedure include assisting the client to lie on the biopsied side, if the iliac crest was entered, or supine, if the vertebral bodies were used, to maintain pressure on the site for 10 to 15 minutes. For sternal punctures, place the client in the supine position or other position of comfort. Provide bed rest for at least 30 minutes after the procedure. Assess puncture site every 10 to 15 minutes for bleeding. Apply an ice bag to the puncture site to alleviate discomfort and prevent bleeding. Assess for infection at the site; note any redness, swelling, or drainage. Administer analgesics to alleviate discomfort. THE PROCEDURE The client is assisted to the desired position depending on the site to be used. In young children, the most frequently chosen site is the proximal tibia; in older children, vertebral bodies T10 to L4 are RETICULOCYTE COUNT Reticulocytes are immature RBCs. As RBC precursors mature (Fig. 1–2), the cell nucleus decreases in size and eventually becomes a dense, structureless Copyright © 2003 F.A. Davis Company 10 SECTION I—Laboratory Tests mass.10 At the same time, the hemoglobin content of the cell increases. Reticulocytes are cells that have lost their nuclei but still retain fragments of mitochondria and other organelles. They also are slightly larger than mature RBCs.11 RBCs normally enter the circulation as reticulocytes and attain the mature form (erythrocytes) in 1 to 2 days. Under the stress of anemia or hypoxia, an increased output of erythropoietin may lead to an increased number of circulating reticulocytes (see Table 1–1). The extent of such an increase depends on the functional integrity of the bone marrow, the severity and duration of anemia or hypoxia, the adequacy of the erythropoietin response, and the amount of available iron.12 For example, a normal reticulocyte count in the presence of a normal hemoglobin level indicates normal marrow activity, whereas a normal reticulocyte count in the presence of a low hemoglobin level indicates an inadequate response to anemia. This may be a result of defective erythropoietin production, bone marrow function, or hemoglobin formation. After blood loss or effective therapy for certain kinds of anemia, an elevated reticulocyte count (reticulocytosis) indicates that the bone marrow is normally responsive and is attempting to replace cells lost or destroyed. Individuals with defects of RBC maturation and hemoglobin production may show a low reticulocyte count (reticulocytopenia) because the cells never mature sufficiently to enter the peripheral circulation. Performing a reticulocyte count involves examining a stained smear of peripheral blood to determine the percentage of reticulocytes in relation to the number of RBCs present. Reference Values Newborns 3.2% of RBCs, declining by 2 mo Infants 2–5% Children 0.5–4% Adults 0.5–2% of RBCs; can be higher in pregnant women Reticulocyte index 1.0 Critical values 20% increase INDICATIONS FOR RETICULOCYTE COUNT Evaluation of the adequacy of bone marrow response to stressors such as anemia or hypoxia: A normal response is indicated by an increase in the reticulocyte count. Failure of the reticulocyte count to increase may indicate depressed bone marrow functioning, defective erythropoietin production, or defective hemoglobin production. Evaluation of anemia of unknown etiology to determine the type of anemia: Elevated reticulocyte counts are found in hemolytic anemias and sickle cell disease. Decreased counts are seen in pernicious anemia, thalassemia, aplastic anemia, and severe iron-deficiency anemia. Monitoring response to therapy for anemia: In iron-deficiency anemia, therapeutic administration of iron should produce reticulocytosis within 3 days and the count should remain elevated until normal hemoglobin levels are achieved. Vitamin B12 therapy for pernicious anemia should cause a prompt, continuing reticulocytosis. Monitoring physiologic response to blood loss: After a single hemorrhagic episode, reticulocytosis should begin within 24 to 48 hours and peak in 4 to 7 days. Persistent reticulocytosis or a second rise in the count indicates continuing blood loss. Confirmation of aplastic crisis in clients with known aplastic anemia as evidenced by a drop in the usually high level of reticulocytes, indicating that RBC production has stopped despite continuing RBC destruction13 NURSING CARE BEFORE THE PROCEDURE Client preparation is the same as that for any study involving the collection of a peripheral blood sample (see Appendix I). THE PROCEDURE If the client is an adult, a venipuncture is performed and the sample is collected in a lavender-topped tube. A capillary sample may be obtained in infants and children as well as in adults for whom venipuncture may not be feasible. NURSING CARE AFTER THE PROCEDURE Care and assessment after the procedure are the same as for any study involving the collection of a peripheral blood sample (see Appendix I). Abnormal values: Note and report fatigue, weakness, and color changes associated with a decrease in counts and pain, and changes in mental state and visual perception associated with an increase in counts. Increased counts in 4 to 7 days indicate Copyright © 2003 F.A. Davis Company CHAPTER 1—Hematology that the therapy to treat loss of RBCs is effective, whereas decreased counts indicate an ineffective production of RBCs, and further testing and evaluation are needed to determine the cause. Assess for continuing blood loss (pulse, blood pressure, skin color, weakness, dizziness). Critical values: Polycythemia with reticulocyte increases of greater than 20 percent requires immediate communication to the physician. Prepare the client for possible phlebotomy to reduce volume of blood and intravenous fluids to reduce viscosity of blood. Administer ordered myelosuppressive drugs. IRON STUDIES Iron plays a principal role in erythropoiesis, because it is necessary for proliferation and maturation of RBCs and for hemoglobin synthesis. Of the body's normal 4 g of iron (somewhat less in women), about 65 percent resides in hemoglobin and about 3 percent in myoglobin. A tiny but vital amount of iron is found in cellular enzymes, which catalyze the oxidation and reduction of iron. The remainder is stored in the liver, bone marrow, and spleen as ferritin or hemosiderin.14 Except for blood transfusions, the only way iron enters the body is orally. Normally, only about 10 percent of ingested iron is absorbed, but up to 20 percent or more can be absorbed in cases of irondeficiency anemia. The body is never able to absorb all ingested iron, no matter how great its need for iron. In addition to dietary sources, iron from wornout or damaged RBCs is available for reuse in erythropoiesis.15 SERUM IRON, TRANSFERRIN, AND TOTAL IRON-BINDING CAPACITY Any iron present in the serum is in transit among the alimentary tract, bone marrow, and available ironstorage forms. Iron travels in the bloodstream bound to transferrin, a protein (-globulin) manufactured by the liver. Unbound iron is highly toxic to the body, but generally much more transferrin is available than that needed for iron transport. Usually, transferrin is only 30 to 35 percent saturated, with a normal range of 20 to 55 percent. If excess transferrin is available in relation to body iron, the percentage saturation is low. Conversely, in situations of iron excess, both serum iron and percentage saturation are high. Measurement of serum iron is accomplished by using a specific color of reagent to quantitate iron after it is freed from transferrin. Transferrin may be measured directly through immunoelectrophoretic and Tests of Hematopoietic Function 11 techniques or indirectly by exposure of the serum to sufficient excess iron such that all the transferrin present can combine with the added iron. The latter result is expressed as total iron-binding capacity (TIBC). The percentage saturation is calculated by dividing the serum iron value by the TIBC value. FERRITIN Iron is stored in the body as ferritin or hemosiderin. Many individuals who are not anemic and who can adequately synthesize hemoglobin may still have decreased iron stores. For example, menstruating women, especially those who have borne children, usually have less storage iron. In contrast, persons with disorders of excess iron storage such as hemochromatosis or hemosiderosis have extremely high serum ferritin levels.16 Serum ferritin levels are used to measure ironstorage status and are obtained by either radioimmunoassay or enzyme-linked immunoassay. The amount of ferritin in the circulation usually is proportional to the amount of storage iron (ferritin and hemosiderin) in body tissues. Note that serum ferritin levels vary according to age and gender (Fig. 1–3). INDICATIONS FOR IRON STUDIES Anemia of unknown etiology to determine cause and type of anemia: Decreased serum iron with increased transferrin levels is seen in iron-deficiency anemia and blood loss. Decreased serum iron and decreased transferrin levels may be seen in disorders involving diminished protein synthesis or defects in iron absorption (e.g., chronic diseases, infections, widespread malignancy, malabsorption syndromes, malnutrition, nephrotic syndrome). Percentage saturation of transferrin Figure 1–3. Serum ferritin levels according to sex and age. (From Hillman, RS, and Finch, CA: Red Cell Manual, ed 7. FA Davis, Philadelphia, 1996, p 64, with permission.) Copyright © 2003 F.A. Davis Company 12 SECTION I—Laboratory Tests Reference Values Conventional Units SI Units Serum Iron Newborns 350–500 mg/dL 62.7–89.5 mmol/L Children 40–200 mg/dL 7.2–35.8 mmol/L Men 60–170 mg/dL 10.7–30.4 mmol/L Women 50–130 mg/dL 9.0–23.3 mmol/L Elderly persons 40–80 mg/dL 7.2–14.3 mmol/L Newborns 60–170 mg/dL 0.6–1.7 g/L Adults 250–450 mg/dL 2.5–4.5 g/L Newborns 65% saturation 0.65 Adults 20–55% saturation 0.20–0.55 Children 100–350 mg/dL 18–63 mmol/L Adults 300–360 mg/dL 54–64 mmol/L Elderly persons 200–310 mg/dL 36–56 mmol/L 20–40 mg/dL 20–40 mg/L Men 50–200 mg/dL 50–200 mg/L (average 100 mg/dL) (avg 100 mg/L) Women (menstruating) 12–100 mg/dL (average 30 mg/dL) (avg 30 mg/L) Adults Transferrin % Saturation (of Transferrin) TIBC Ferritin Children Adults may be normal if serum iron and transferrin levels are proportionately decreased; if the problem is solely one of protein homeostasis (with normal iron stores), percentage saturation will be high. Support for diagnosing hemochromatosis or other disorders of iron metabolism and storage: Serum iron and ferritin levels may be elevated in hemochromatosis and hemosiderosis; percentage saturation of transferrin is elevated, whereas TIBC is decreased. Serum iron levels can be elevated in lead poisoning, after multiple blood transfusions, and in severe hemolytic disorders that cause release of iron from damaged RBCs. 12–100 mg/L Monitoring hematologic responses during pregnancy, when serum iron is usually decreased, transferrin levels are increased (in the third trimester), percentage saturation is low, TIBC may be increased, and ferritin may be decreased (Note: Transferrin levels may be increased in women taking oral contraceptives, whereas ferritin levels may be decreased in women who are menstruating or who have borne children.) NURSING CARE BEFORE THE PROCEDURE Client preparation is the same as that for any study involving the collection of a peripheral blood sample (see Appendix I). Copyright © 2003 F.A. Davis Company CHAPTER 1—Hematology and Tests of Hematopoietic Function 13 Reference Values Conventional Units SI Units Vitamin B12 Serum 200–900 pg/mL 148–664 pmol/L Folic acid Serum 1.8–9 ng/mL 4–20 nmol/L RBCs 95–500 ng/mL 215–1133 nmol/L Blood for serum iron and TIBC should be drawn in the morning, in the fasting state, and 24 hours or more after discontinuing iron-containing medications.17 THE PROCEDURE A venipuncture is performed and the sample collected in a red-topped tube. A capillary sample may be obtained in infants and children as well as in adults for whom venipuncture may not be feasible. NURSING CARE AFTER THE PROCEDURE Care and assessment after the procedure are the same as for any study involving the collection of a peripheral blood sample (see Appendix I). Food, fluids, and medications withheld before the test may be resumed after the sample is obtained. Complications and precautions: Note and report signs and symptoms of anemia: decreases in test levels, fatigue and weakness, increased pulse, exertional dyspnea, and dizziness. If anemia is caused by blood loss, prepare to administer a transfusion of blood products. If anemia is caused by iron deficiency, administer ordered oral or parenteral (intramuscular) iron supplement and instruct client in dietary inclusion of foods high in iron content. After 4 to 7 days, check iron studies, RBC count, reticulocyte count, and hemoglobin levels to see whether iron stores have been replenished. VITAMIN B12 AND FOLIC ACID STUDIES Vitamin B12 (cyanocobalamin) and folic acid (pteroylglutamic acid) are essential for the production and maturation of erythrocytes. Both must be present for normal DNA replication and cell division. In humans, vitamin B12 is obtained only by eating animal proteins, milk, and eggs, which places strict vegetarians at risk for developing cobalamin deficiency; hydrochloric acid (HCl) and intrinsic factor are required for absorption. Folic acid (or folate) is present in liver and in many foods of vegetable origin such as lima beans, kidney beans, and dark-green leafy vegetables. Note that canning and prolonged cooking destroy folate. Normally functioning intestinal mucosa is necessary for absorption of both vitamin B12 and folic acid. Vitamin B12 is normally stored in the liver in sufficient quantity to withstand 1 year of zero intake. In contrast, most of the folic acid absorbed goes directly to the tissues, with a smaller amount stored in the liver. Folate stores are adequate for only 2 to 4 months. INDICATIONS FOR VITAMIN B12 AND FOLIC ACID STUDIES Determination of the cause of megaloblastic anemia: Diagnosis of pernicious anemia, a megaloblastic anemia characterized by vitamin B12 deficiency despite normal dietary intake Diagnosis of megaloblastic anemia caused by deficient folic acid intake or increased folate requirements (e.g., in pregnancy and hemolytic anemias) or both, as indicated by decreased serum levels of folic acid Monitoring response to disorders that may lead to vitamin B12 deficiency (e.g., gastric surgery, agerelated atrophy of the gastric mucosa, surgical resection of the ileum, intestinal parasites, overgrowth of intestinal bacteria) Monitoring response to disorders that may lead to folate deficiency (e.g., disease of the small intestine, sprue, cirrhosis, chronic alcoholism, uremia, some malignancies)18 Monitoring effects of drugs that are folic acid antagonists (e.g., alcohol, anticonvulsants, antimalarials, and certain drugs used to treat leukemia)19 Monitoring effects of prolonged parenteral nutrition NURSING CARE BEFORE THE PROCEDURE Client preparation is the same as that for any study involving the collection of a peripheral blood sample (see Appendix I). Copyright © 2003 F.A. Davis Company 14 SECTION I—Laboratory Tests Samples should be drawn after the client has fasted for 8 hours and before injections of vitamin B12 have been given. Alcohol also should be avoided for 24 hours before the test. THE PROCEDURE A venipuncture is performed and the sample collected in a red-topped tube. A capillary sample may be obtained in infants and children as well as in adults for whom venipuncture may not be feasible. The difference between men and women results partly from menstrual blood loss in women and partly from the effects of androgens in men. Castration of men usually causes hemoglobin and hematocrit to decline to nearly the same levels as those of women. Note that a decline in erythrocytes is experienced by both genders in old age.21 More detailed discussions of the RBC and WBC components of the CBC are included in succeeding sections of this chapter. Platelets are discussed in Chapter 2. NURSING CARE AFTER THE PROCEDURE Care and assessment after the procedure are the same as for any study involving the collection of a peripheral blood sample (see Appendix I). Foods and drugs withheld before the test may be resumed after the sample is obtained. Complications and precautions (anemia): Note and report folic acid levels of less than 4 ng and a normal level of vitamin B12, indicating folic acid anemia. Prepare to administer ordered oral replacement therapy of folic acid; dosage and duration depend on the cause of the deficiency. Perform nursing activities for vitamin B12 deficiency as in pernicious anemia diagnosed by the Schilling test (see Chapter 20). COMPLETE BLOOD COUNT A CBC includes (1) enumeration of the cellular elements of the blood, (2) evaluation of RBC indices, and (3) determination of cell morphology by means of stained smears. Counting is performed by automated electronic devices capable of rapid analysis of blood samples with a measurement error of less than 2 percent.20 Reference values for the CBC vary across the life cycle and between the genders. In the neonate, when oxygen demand is high, the number of erythrocytes also is high. As demand decreases, destruction of the excess cells results in decreased erythrocyte, hemoglobin, and hematocrit levels. During childhood, RBC levels again rise, although hemoglobin levels may decrease slightly. In prepubertal children, normal erythrocyte and hemoglobin levels are the same for boys and girls. During puberty, however, values for boys rise, whereas values for girls decrease. In men, these higher values persist to age 40 or 50, decline slowly to age 70, and then decrease rapidly thereafter. In women, the drop in hemoglobin and hematocrit that begins with puberty reverses at about age 50 but never rises to prepubertal levels or to that of men of the same age. Reference Values The components of the CBC and their reference values across the life cycle are shown in Table 1–4. INDICATIONS FOR A COMPLETE BLOOD COUNT Because the CBC provides much information about the overall health of the individual, it is an essential component of a complete physical examination, especially when performed on admission to a health-care facility or before surgery. Other indications for a CBC are as follows: Suspected hematologic disorder, neoplasm, or immunologic abnormality History of hereditary hematologic abnormality Suspected infection (local or systemic, acute or chronic) Monitoring effects of physical or emotional stress Monitoring desired responses to drug therapy and undesired reactions to drugs that may cause blood dyscrasias (Table 1–5) Monitoring progression of nonhematologic disorders such as chronic obstructive pulmonary disease, malabsorption syndromes, malignancies, and renal disease NURSING CARE BEFORE THE PROCEDURE Client preparation is the same as that for any study involving the collection of a peripheral blood sample (see Appendix I). THE PROCEDURE A venipuncture is performed and the sample collected in a lavender-topped tube. A capillary sample may be obtained in infants and children, as well as in adults for whom venipuncture may not be feasible. NURSING CARE AFTER THE PROCEDURE Care and assessment after the procedure are the Copyright © 2003 F.A. Davis Company TABLE 1–4 • Reference Values for Complete Blood Count Adult CBC Component Red blood cells (RBCs) Newborn 1 Mo 4.8–7.1 million/mm3 4.8–7.1 10 /L (SI units) 12 6 Mo 1–10 Yr Male Female 4.1–6.4 million/mm3 3.8–5.5 million/mm3 4.5–4.8 million/mm3 4.6–6.2 million/mm3 4.2–5.4 million/mm3 35–49% 30–40% 35–41% 40–54% 38–47% Hemoglobin (Hgb) 14–24 g/L (SI units) 11–20 g/dL 10–15 g/dL 11–16 g/dL 13.5–18 g/dL 12–16 g/dL 140–240 g/L (SI units) 110–200 g/L 100–150 g/L 110–160 g/L 135–180 g/L 120–160 g/L 96–108 m3 82–91 3 — — 80–94 m3 81–99 m3 96–108 fL (SI units) 82–91 fL — — 80–94 fL 81–99 fL 32–34 pg 27–31 pg — — 27–31 pg 32–33% 32–36% — — 32–36% 320–330 S/L (SI units) 320–360 S/L RBC indices MCV* † MCH MCHC ‡ Stained RBC examination White blood cells (WBCs) 320–360 S/L Normochromic and normocytic for all age groups and both sexes (see p. 23) 9,000–30,000/mm3 6,000–18,000/mm3 6,000–16,000/mm3 5,000–13,000/mm3 5,000–10,000/mm3 9,000–30,000 10 /L (SI units) 9 (Continued on following page) and Tests of Hematopoietic Function 4.4–64% CHAPTER 1—Hematology Hematocrit (Hct) 15 Copyright © 2003 F.A. Davis Company 16 • Reference Values for Complete Blood Count (Continued) Adult CBC Component Newborn 1 Mo 6 Mo 1–10 Yr Male Female Neutrophils 45% by 1 wk 40% by 4 wk 32% 60% after age 2 yr — 54–75% (3000–7500/mm3) Bands — — — — — 3–8% (150–700/mm3) Eosinophils — — — 0–3% — 1–4% (50–400/mm3) Basophils — — — 1–3% — 0–1% (25–100/mm3) Monocytes — — — 4–9% — 2–8% (100–500/mm3) Lymphocytes 41% by 1 wk 56% by 4 wk 61% 59% after age 2 yr — 25–40% (1500–4500/mm3) T lymphocytes — — — — — 60–80% of lymphocytes B lymphocytes — — — — Platelets 140,000–300,000/mm3 150,000–390,000/ mm3 200,000–473,000/ mm3 150,000–450,000/ mm3 150,000–450,000/mm3 140–300 109/L (SI units) 150–390 109/L 200–473 109/L 150–450 109/L 150–450 109/L * Mean corpuscular volume. † Mean corpuscular hemoglobin. ‡ Mean corpuscular hemoglobin concentration. 10–20% of lymphocytes Tests Differential WBC SECTION I—Laboratory TABLE 1–4 Copyright © 2003 F.A. Davis Company CHAPTER 1—Hematology TABLE 1–5 • and Tests of Hematopoietic Function 17 Drugs That May Cause Blood Dyscrasias Generic Name or Class Trade Names Acetaminophen and acetaminophen compounds Bancap, Capital, Colrex, Comtrex, Darvocet-N, Datril, Dolene, Duradrin, Duradyne, Esgic, Excedrin, Liquiprin, Midrin, Neopap Supprettes, NyQuil, Ornex, Panadol, Parafon Forte, Percogesic, Phrenilin, Sedapap, Sinarest, Sinutab, Supac, Tylenol, Tempra, Tylenol with Codeine, Valadol, Vanquish, Wygesic Acetophenazine maleate Tindal Aminosalicylic acid Pamisyl, PAS, Rezipas Amphotericin B Fungizone, Mysteclin F Antineoplastic agents Arsenicals Carbamazepine Tegretol Chloramphenicol Chloromycetin Chloroquine Aralen Ethosuximide (methsuximide, phensuximide) Zarontin Furazolidone Furoxone Haloperidol Haldol Hydantoin derivatives Ethotoin Peganone Mephenytoin Mesantoin Phenytoin Dilantin, Diphenylan Hydralazine Apresazide, Apresoline, Bolazine, Ser-Ap-Es, Serpasil-Apresoline Hydroxychloroquine sulfate Plaquenil Indomethacin Indocin Isoniazid INH, Nydrazid, Rifamate MAO inhibitors Eutonyl, Nardil, Parnate Mefenamic acid Ponstel Mepacrine Atabrine Mephenoxalone Lenetron Mercurial diuretics Thiomerin Metaxalone Skelaxin Methaqualone Quaalude, Sopor Methyldopa Aldoclor, Aldomet, Aldoril Nitrites Nitrofurantoin Cyantin, Furadantin, Macrodantin Novobiocin Albamycin Oleandomycin Matromycin (Continued on following page) Copyright © 2003 F.A. Davis Company 18 SECTION I—Laboratory TABLE 1–5 • Tests Drugs That May Cause Blood Dyscrasias (Continued) Generic Name or Class Trade Names Oxyphenbutazone Oxalid, Tandearil Paramethadione Paradione Penicillamine Cuprimine, Depen Penicillins Phenacemide Phenurone Phenobarbital Phenylbutazone Azolid, Butazolidin Phytonadione AquaMEPHYTON, Konakion Primaquine Primidone Mysoline Pyrazolone derivatives Butazolidin, Tandearil, Oxalid Pyrimethamine Daraprim Rifampin Rifadin, Rifamate, Rimactane Radioisotopes Spectinomycin Trobicin Sulfonamides Mafenide Sulfamylon cream Phthalylsulfathiazole Sulfathalidine Sulfabenzamide Sultrin vaginal cream Sulfacetamide Bleph-10, Cetamide ointment, Isopto Cetamide, Sulamyd, Sultrin vaginal cream Sulfachloropyridazine Sonilyn Sulfacytine Renoquid Sulfadiazine Silvadene Sulfameter Sulla Sulfamethiozole Thiosulfil Forte Sulfamethoxazole Azo Gantanol, Bactrim, Gantanol, Septra Sulfamethoxypyridazine Midicel Sulfanilamide AVC vaginal cream Sulfasalazine Azulfidine Sulfathiazole Sultrin vaginal cream, Triple Sulfa cream Sulfinpyrazone Anturane Sulfisoxazole Azo Gantrisin, Gantrisin Sulfones Dapsone DDS Sulfoxone Copyright © 2003 F.A. Davis Company CHAPTER 1—Hematology TABLE 1–5 • and Tests of Hematopoietic Function 19 Drugs That May Cause Blood Dyscrasias Generic Name or Class Trade Names Sulfonylureas Acetohexamide Dymelor Chlorpropamide Diabinese Tolazamide Tolinase Tolbutamide Orinase Tetracyclines Achromycin Chlortetracycline Aureomycin Demeclocycline Declomycin Doxycycline Doxychel, Doxy, Vibramycin, Vibra-Tabs Meclocycline Meclan Methacycline Rondomycin Minocycline Minocin Oxytetracycline Oxlopar, Terramycin Thiazide diuretics (rare hematologic side effects) Ademol, Diuril, Enduron, Exna, Naturetin, Naqua, Renese, Saluron Thiocyanates Trimethadione Tridione Tripelennamine Pyribenzamine, PBZ Troleandomycin Cyclamycin, Tao capsules and suspension Valproic acid Valproate Vitamin A Aquasol A, Alphalin same as for any study involving the collection of a peripheral blood sample (see Appendix I). Abnormal range of values: Note and report decreases in individual or entire CBC (pancytopenia) panel. Prepare to administer drugs and treatments, or both, that have been ordered to manage anemia (RBC, hematocrit [Hct], hemoglobin [Hgb], RBC indices), clotting process (platelet), or infectious process (WBC, differential). ERYTHROCYTE STUDIES The mature RBC (erythrocyte) is a biconcave disk with an average life span of 120 days. Because it lacks a nucleus and mitochondria, it is unable to synthesize protein, and its limited metabolism is barely enough to sustain it. Erythrocytes function primarily as containers for Hgb. As such, they transport oxygen from the lungs to all body cells and transfer carbon dioxide from the cells to the organs of excretion. The RBC is resilient and capable of extreme changes in shape. It is admirably designed to survive its many trips through the circulation.22 Old, damaged, and abnormal erythrocytes are removed mainly by the spleen and also by the liver and the red bone marrow. The iron is returned to plasma transferrin and is transported back to the erythroid marrow or stored within the liver and spleen as ferritin and hemosiderin. The bilirubin component of Hgb is carried by plasma albumin to the liver, where it is conjugated and excreted into the bile. Most of this conjugated bilirubin is ultimately excreted in the stool, although some appears in the urine or is returned to bile. The hematologist determines the numbers, structure, color, size, and shape of erythrocytes; the types Copyright © 2003 F.A. Davis Company 20 SECTION I—Laboratory Tests and amount of Hgb they contain; their fragility; and any abnormal components. INDICATIONS FOR AN ERYTHROCYTE (RBC) COUNT Routine screening as part of a CBC Suspected hematologic disorder involving RBC destruction (e.g., hemolytic anemia) Monitoring effects of acute or chronic blood loss Monitoring response to drug therapy that may alter the RBC count (see Table 1–5) Monitoring clients with disorders associated with elevated RBC counts (e.g., polycythemia vera, chronic obstructive pulmonary disease) Monitoring clients with disorders associated with decreased RBC counts (e.g., malabsorption syndromes, malnutrition, liver disease, renal disease, hypothyroidism, adrenal dysfunction, bone marrow failure) ERYTHROCYTE (RBC) COUNT The erythrocyte (RBC) count, a component of the CBC, is the determination of the number of RBCs per cubic millimeter. In international units, this is expressed as the number of RBCs per liter of blood. The test is less significant by itself than it is in computing Hgb, Hct, and RBC indices. Many factors influence the level of circulating erythrocytes. Decreased numbers are seen in disorders involving impaired erythropoiesis excessive blood cell destruction (e.g., hemolytic anemia), and blood loss, and in chronic inflammatory diseases. A relative decrease also may be seen in situations with increased body fluid in the presence of a normal number of RBCs (e.g., pregnancy). Increases in the RBC count are most commonly seen in polycythemia vera, chronic pulmonary disease with hypoxia and secondary polycythemia, and dehydration with hemoconcentration. Excessive exercise, anxiety, and pain also produce higher RBC counts. Many drugs can cause a decrease in circulating RBCs (see Table 1–5), whereas a few drugs, such as methyldopa and gentamicin, can cause an increase.23 NURSING CARE BEFORE THE PROCEDURE Client preparation is the same as that for any study involving the collection of a peripheral blood sample (see Appendix I). THE PROCEDURE A venipuncture is performed and the sample collected in a lavender-topped tube. A capillary sample may be obtained in infants and children as well as in adults for whom venipuncture may not be feasible. INTERFERING FACTORS NURSING CARE AFTER THE PROCEDURE Excessive exercise, anxiety, pain, and dehydration may lead to false elevations. Hemodilution in the presence of a normal number of RBCs may lead to false decreases (e.g., excessive administration of intravenous fluids, normal pregnancy). Many drugs may cause a decrease in circulating RBCs (see Table 1–5). Drugs such as methyldopa and gentamicin may cause an elevated RBC count. Care and assessment after the procedure are the same as for any study involving the collection of a peripheral blood sample (see Appendix I). Anemia: Note and report signs and symptoms of anemia associated with decreased counts in combination with Hgb and Hct decreases. Prepare to administer ordered oral or parenteral iron preparation or a transfusion of whole blood or packed RBCs. Prepare for phlebotomy if levels are Reference Values Conventional Units SI Units Newborns 4.8–7.1 million/mm 3 4.8–7.1 1012/L 1 mo 4.1–6.4 million/mm3 4.1–6.4 1012/L 6 mo 3.8–5.5 million/mm3 3.8–5.5 1012/L 1–10 yr 4.5–4.8 million/mm3 4.5–4.8 1012/L Men 4.6–6.2 million/mm3 4.6–6.2 1012/L Women 4.2–5.4 million/mm3 4.2–5.4 1012/L Adults Copyright © 2003 F.A. Davis Company CHAPTER 1—Hematology increased in polycythemia vera or secondary polycythemia. HEMATOCRIT Blood consists of a fluid portion (plasma) and a solid portion that includes RBCs, WBCs, and platelets. More than 99 percent of the total blood cell mass is composed of RBCs. The Hct or packed RBC volume measures the proportion of RBCs in a volume of whole blood and is expressed as a percentage. Several methods can be used to perform the test. In the classic method, anticoagulated venous blood is pipetted into a tube 100 mm long and then centrifuged for 30 minutes so that the plasma and blood cells separate. The volumes of packed RBCs and plasma are read directly from the millimeter marks along the side of the tube. In the micro method, venous or capillary blood is used to fill a small capillary tube, which is then centrifuged for 4 to 5 minutes. The proportions of plasma and RBCs are determined by means of a calibrated reading device. Both techniques allow visual estimation of the volume of WBCs and platelets.24 With the newer, automated methods of cell counting, the Hct is calculated indirectly as the product of the RBC count and mean cell volume. Although this method is generally quite accurate, certain clinical situations may cause errors in interpreting the Hct. Abnormalities in RBC size and extremely elevated WBC counts may produce false Hct values. Elevated blood glucose and sodium may produce elevated Hct values because of the resultant swelling of the erythrocyte.25 Normally, the Hct parallels the RBC count. Thus, factors influencing the RBC count also affect the results of the Hct. Reference Values Conventional Units SI Units Newborns 44–64% 0.44–64 1 mo 35–49% 0.35–0.49 6 mo 30–40% 0.30–0.40 1–10 yr 35–41% 0.35–0.41 Men 40–54% 0.40–0.54 Women 38–47% 0.38–0.47 Adults and Tests of Hematopoietic Function 21 INTERFERING FACTORS Abnormalities in RBC size and extremely elevated WBC counts may alter Hct values. Elevated blood glucose and sodium may produce elevated Hct values because of swelling of the erythrocyte. Factors that alter the RBC count such as hemodilution and dehydration also influence the Hct. INDICATIONS FOR A HEMATOCRIT TEST Routine screening as part of a CBC Along with an Hgb (i.e., an "H and H"), to monitor blood loss and response to blood replacement Along with an Hgb, to evaluate known or suspected anemia and related treatment Along with an Hgb, to monitor hematologic status during pregnancy Monitoring responses to fluid imbalances or to therapy for fluid imbalances: A decreased Hct may indicate hemodilution. An increased Hct may indicate dehydration. NURSING CARE BEFORE THE PROCEDURE Client preparation is the same as that for any study involving the collection of a peripheral blood sample (see Appendix I). THE PROCEDURE The volume of the sample needed depends on the method used to determine the Hct. With the exception of the classic method of Hct determination, a capillary sample is usually sufficient to perform the test. If a venipuncture is performed, the sample is collected in a lavender-topped tube. NURSING CARE AFTER THE PROCEDURE Care and assessment after the procedure are the same as for any study involving the collection of a peripheral blood sample (see Appendix I). Critical values: Notify the physician at once if the Hct is greater than 60 percent or less than 14 percent. Prepare the client for possible transfusion of blood products or infusion of intravenous fluids and for further procedures to evaluate the cause or source of the blood loss or hemoconcentration. HEMOGLOBIN Critical values 14% or 60% 0.14–0.60 Note: Values vary across the life cycle and between genders. Hemoglobin is the main intracellular protein of the RBC. Its primary function is to transport oxygen to the cells and to remove carbon dioxide from them for excretion by the lungs. The Hgb molecule consists of two main components: heme and globin. Copyright © 2003 F.A. Davis Company 22 SECTION I—Laboratory Tests Heme is composed of the red pigment porphyrin and iron, which is capable of combining loosely with oxygen. Globin is a protein that consists of nearly 600 amino acids organized into four polypeptide chains. Each chain of globin is associated with a heme group. Each RBC contains approximately 250 million molecules of hemoglobin, with some erythrocytes containing more hemoglobin than others. The oxygen-binding, -carrying, and -releasing capacity of Hgb depends on the ability of the globin chains to shift position normally during the oxygenation–deoxygenation process. Structurally abnormal chains that are unable to shift normally have decreased oxygen-carrying ability. This decreased oxygen transport capacity is characteristic of anemia. Hemoglobin also functions as a buffer in the maintenance of acid–base balance. During transport, carbon dioxide (CO2) reacts with water (H2O) to form carbonic acid (H2CO3). This reaction is speeded by carbonic anhydrase, an enzyme contained in RBCs. The carbonic acid rapidly dissociates to form hydrogen ions (H) and bicarbonate ions (HCO3–). The hydrogen ions combine with the Hgb molecule, thus preventing a buildup of hydrogen ions in the blood. The bicarbonate ions diffuse into the plasma and play a role in the bicarbonate buffer system. As bicarbonate ions enter the bloodstream, chloride ions (Cl) are repelled and move back into the erythrocyte. This "chloride shift" maintains the electrical balance between RBCs and plasma.26 Hemoglobin determinations are of greatest use in the evaluation of anemia, because the oxygen-carrying capacity of the blood is directly related to the Hgb level rather than to the number of erythrocytes. To interpret results accurately, the Hgb level must be determined in combination with the Hct level. Normally, Hgb and Hct levels parallel each other and are commonly used together to express the degree of anemia. The combined values are also useful in evaluating situations involving blood loss and related treatment. The Hct level is normally three times the Hgb level. If erythrocytes are abnormal in shape or size or if Hgb manufacture is defective, the relationship between Hgb and Hct is disproportionate.27,28 Reference Values Conventional Units SI Units Newborns 14–24 g/dL 140–240 g/L 1 mo 11–20 g/dL 110–200 g/L 6 mo 10–15 g/dL 100–150 g/L 1–10 yr 11–16 g/dL 110–160 g/L 13.5–18 g/dL 135–180 g/L 12–16 g/dL 120–160 g/L 6.0 g/dL 200 g/dL 60 g/L 200 g/L Adults Men Women Critical values Note: Ratio of hemoglobin to hematocrit 3:1. ate known or suspected anemia and related treatment Along with an Hct, to monitor blood loss and response to blood replacement Along with an Hct, to monitor hematologic status during pregnancy NURSING CARE BEFORE THE PROCEDURE Client preparation is the same as that for any study involving the collection of a peripheral blood sample (see Appendix I). THE PROCEDURE A venipuncture is performed and the sample collected in a lavender-topped tube. A capillary sample may be obtained in infants and children as well as in adults for whom venipuncture may not be feasible. NURSING CARE AFTER THE PROCEDURE Care and assessment after the procedure are the same as for any study involving the collection of a peripheral blood sample (see Appendix I). Critical values: Notify the physician at once if the Hgb is less than 6.0 g/dL. Prepare the client for possible transfusion of blood products and for further procedures to evaluate cause or source of blood loss. INTERFERING FACTORS Factors that alter the RBC count may also influence Hgb levels INDICATIONS FOR HEMOGLOBIN DETERMINATION Routine screening as part of a CBC Along with an Hct (i.e., an "H and H"), to evalu- RED BLOOD CELL INDICES RBC indices are calculated mean values that reflect the size, weight, and Hgb content of individual erythrocytes. They consist of the mean corpuscular volume (MCV), the mean corpuscular hemoglobin (MCH), and the mean corpuscular hemoglobin Copyright © 2003 F.A. Davis Company CHAPTER 1—Hematology TABLE 1–6 Microcytic, normochromic Microcytic, hypochromic Macrocytic, normochromic 23 Classification of Anemias MCV* (mm3) MCH† (pg) MCHC‡ (%) Sepsis, hemorrhage, hemolysis, drug-induced aplastic anemia, radiation, hereditary spherocytosis 82–92 25–30 32–36 Renal disease, infection, liver disease, malignancies 80 20–25 27 Iron deficiency, lead poisoning, thalassemia, rheumatoid arthritis 50–80 12–25 25–30 95–150 30–50 32–36 Anemia Normocytic, normochromic • and Tests of Hematopoietic Function Examples of Causes Vitamin B12 and folic acid deficiency, some drugs, pernicious anemia * Mean corpuscular volume. † Mean corpuscular hemoglobin. ‡ Mean corpuscular hemoglobin concentration. concentration (MCHC). MCV indicates the volume of the Hgb in each RBC, MCH is the weight of the Hgb in each RBC, and MCHC is the proportion of Hgb contained in each RBC. MCHC is a valuable indicator of Hgb deficiency and of the oxygen-carrying capacity of the individual erythrocyte. A cell of abnormal size, abnormal shape, or both may contain an inadequate proportion of Hgb. RBC indices are used mainly in identifying and classifying types of anemias. Anemias are generally classified according to RBC size and Hgb content. Cell size is indicated by the terms normocytic, microcytic, and macrocytic. Hemoglobin content is indicated by the terms normochromic, hypochromic, and hyperchromic. Table 1–6 shows anemias classified according to these terms and in relation to the results of RBC indices. To calculate the RBC indices, the results of an RBC count, Hct, and Hgb are necessary. Thus, factors that influence these three determinations (e.g., abnormalities of RBC size or extremely elevated WBC counts) may result in misleading RBC indices. For this reason, a stained blood smear may be used to compare appearance with calculated values and to determine the etiology of identified abnormalities. INTERFERING FACTORS Because RBC indices are calculated from the results of the RBC count, Hgb, and Hct, factors that influ- Reference Values Men MCV Women 80–94 m 3 Newborns 81–99 m 3 SI Units 96–108 m 3 81–99 fL (women) 96–108 fL (newborns) MCH 27–31 pg 27–31 pg 32–34 pg 32–34 pg (women) 32–34 pg (newborns) MCHC 32–36% 32–36% 32–33% 320–360 g/L (women) 320–330 g/L (newborns) Normal values for RBC indices are shown in Table 1–4 in relation to the CBC and also are repeated above for adults. Values in newborn infants are slightly different, but adult levels are achieved within approximately 1 month of age. Copyright © 2003 F.A. Davis Company 24 SECTION I—Laboratory Tests ence the latter three tests (e.g., abnormalities of RBC size, extremely elevated WBC counts) also influence RBC indices. INDICATIONS FOR RED BLOOD CELL INDICES Routine screening as part of a CBC Identification and classification of anemias (see Table 1–6) NURSING CARE BEFORE THE PROCEDURE Client preparation is the same as that for any study involving the collection of a peripheral blood sample (see Appendix I). THE PROCEDURE A venipuncture is performed and the sample collected in a lavender-topped tube. A capillary sample may be obtained in infants and children as well as in adults for whom venipuncture may not be feasible. NURSING CARE AFTER THE PROCEDURE Care and assessment after the procedure are the same as for any study involving the collection of a peripheral blood sample (see Appendix I). TABLE 1–7 Descriptive Term Macrocytosis • STAINED RED BLOOD CELL EXAMINATION The stained RBC examination (RBC morphology) involves examination of RBCs under a microscope. It is usually performed to compare the actual appearance of the cells with the calculated values for RBC indices. Cells are examined for abnormalities in color, size, shape, and contents. The test is performed by spreading a drop of fresh anticoagulated blood on a glass slide. The addition of stain to the specimen is used to enhance RBC characteristics. As with RBC indices, RBC color is described as normochromic, hypochromic, or hyperchromic, indicating, respectively, normal, reduced, or elevated amounts of Hgb. Cell size may be described as normocytic, microcytic, or macrocytic, depending on whether cell size is normal, small, or abnormally large, respectively. Cell shape is described using terms such as poikilocyte, anisocyte, leptocyte, and spherocyte (Table 1–7). The cells are examined also for inclusions or abnormal cell contents, for example, Heinz bodies, Howell-Jolly bodies, Cabot's rings, and siderotic granules (Table 1–8). Red Blood Cell Abnormalities Seen on Stained Smear Observation Significance Cell diameter 8 m Megaloblastic anemias MCV* 95 m3 Severe liver disease Hypothyroidism Microcytosis Cell diameter 6 m Iron-deficiency anemia MCV 80 m Thalassemias MCHC† 27 Anemia of chronic disease Hypochromia Increased zone of central pallor Diminished Hgb content Hyperchromia Microcytic, hyperchromic cells Chronic inflammation Increased bone marrow stores of iron Defect in ability to use iron for Hgb synthesis Polychromatophilia Presence of red cells not fully hemoglobinized Reticulocytosis Poikilocytosis Variability of cell shape Sickle cell disease 3 Microangiopathic hemolysis Leukemias Extramedullary hematopoiesis Marrow stress of any cause Copyright © 2003 F.A. Davis Company CHAPTER 1—Hematology TABLE 1–7 • 25 Red Blood Cell Abnormalities Seen on Stained Smear Descriptive Term Anisocytosis and Tests of Hematopoietic Function Observation Significance Reticulocytosis Variability of cell size Transfusing normal blood into microcytic or macrocytic cell population Leptocytosis Spherocytosis Hypochromic cells with small central zone of Hgb ("target cells") Thalassemias Cells with no central pallor, loss of biconcave shape Loss of membrane relative to cell volume Obstructive jaundice Hereditary spherocytosis Schistocytosis MCHC high Accelerated red blood cell destruction by reticuloendothelial system Acanthocytosis Presence of cell fragments in circulation Increased intravascular mechanical trauma Echinocytosis Irregularly spiculated surface Microangiopathic hemolysis Irreversibly abnormal membrane lipid content Liver disease Abetalipoproteinemia Regularly spiculated cell surface Reversible abnormalities of membrane lipids High plasma-free fatty acids Bile acid abnormalities Effects of barbiturates, salicylates, and so on Stomatocytosis Elongated, slitlike zone of central pallor Hereditary defect in membrane sodium metabolism Severe liver disease Elliptocytosis Oval cells Hereditary anomaly, usually harmless Source: Adapted from Sacher, RA, and McPherson, RA: Widmann's Clinical Interpretation of Laboratory Tests, ed 11. FA Davis, Philadelphia, 2000 p. 68, with permission. * Mean corpuscular volume. †Mean corpuscular hemoglobin concentration. Reference Values In a normal smear, all cells are uniform in color, size, and shape and are free of abnormal contents. A normal RBC may be described as a normochromic, normocytic cell. INDICATIONS FOR A STAINED RED BLOOD CELL EXAMINATION Abnormal calculated values for RBC indices Evaluation of anemia and related disorders involving RBCs (see Tables 1–6, 1–7, and 1–8) NURSING CARE BEFORE THE PROCEDURE Client preparation is the same as that for any study involving the collection of a peripheral blood sample (see Appendix I). THE PROCEDURE A venipuncture is performed and the sample collected in a lavender-topped tube. A capillary Copyright © 2003 F.A. Davis Company 26 SECTION I—Laboratory TABLE 1–8 • Tests Types of Abnormal Red Blood Cell Inclusions and Their Causes Type (Composition) Heinz bodies (denatured Hgb) Causes of Inclusions -Thalassemia G-6-PD deficiency Hemolytic anemias Methemoglobinemia Splenectomy Drugs: analgesics, antimalarials, antipyretics, nitrofurantoin (Furadantin), nitrofurazone (Furacin), phenylhydrazine, sulfonamides, tolbutamide, vitamin K (large doses) Basophilic stippling (residual cytoplasmic RNA) Anemia caused by liver disease Lead poisoning Thalassemia Howell-Jolly bodies (fragments of residual DNA) Splenectomy Intense or abnormal RBC production resulting from hemolysis or inefficient erythropoiesis Cabot's rings (composition unknown) Same as for Howell-Jolly bodies Siderotic granules (ironcontaining granules) Abnormal iron metabolism Abnormal hemoglobin manufacture sample may be obtained in infants and children as well as in adults for whom venipuncture may not be feasible. NURSING CARE AFTER THE PROCEDURE Care and assessment after the procedure are the same as for any study involving the collection of a peripheral blood sample (see Appendix I). HEMOGLOBIN ELECTROPHORESIS The Hgb molecule consists of four polypeptide globin chains and four heme components containing iron and the red pigment porphyrin. Hemoglobin formation is genetically determined, and the types of globin chains normally formed are termed alpha ( ), beta (), gamma ( ), and delta ( ). Combinations of these chains form various types of Hgb. Disorders of synthesis and production of globin chains result in the formation of abnormal Hgb. Hemoglobin electrophoresis is a technique for identifying the types of Hgb present and for determining the percentage of each type. Exposed to an electrical current, the several types of Hgb migrate toward the positive pole at different rates. The patterns created are compared with standard patterns. At birth, most RBCs contain fetal hemoglobin (Hgb F), which is made up of two chains and two chains. Within a few months, through sequential suppression and activation of individual genes, Hgb F largely disappears and is replaced by adult hemoglobin (Hgb A). Hgb A, composed of two chains and two chains, makes up more than 95 percent of Hgb in adults. A minor type of Hgb, Hgb A2, consisting of two chains and two chains, also is found in small amounts (2 to 3 percent) in adults. Traces of Hgb F persist throughout life (Fig. 1–4).29 More than 150 genetic abnormalities in the Hgb molecule have been identified. These are termed thalassemias and hemoglobinopathies. Thalassemias are genetic disorders in globin chain synthesis that result in decreased production rates of - or globin chains. Hemoglobinopathies refer to disorders involving an abnormal amino acid sequence in the globin chains. In -thalassemia, for example, production of chains and Hgb A is decreased. The oversupply of chains results in the formation of hemoglobin H (Hgb H), which consists of four chains (Fig. 1–5). Complete absence of a chain production (homozygous thalassemia A) is incompatible with life and generally results in stillbirth during the second trimester of pregnancy. The cord blood of such fetuses shows high levels of hemoglobin Barts, a type Copyright © 2003 F.A. Davis Company CHAPTER 1—Hematology Figure 1–4. Changes in hemoglobin with development. (From Hillman, RS, and Finch, CA: Red Cell Manual, ed 7. FA Davis, Philadelphia, 1996, p. 11, with permission.) of Hgb that evolves from unpaired chains. Hemoglobin Barts itself has such a high affinity for oxygen that it releases none to the tissues. In -thalassemia minor, a decrease is seen in chain production and, therefore, a reduction in the amount of Hgb A formed. In -thalassemia major, all -chain production is lost and no Hgb A is formed. The chains are then used to form Hgb F and Hgb A2. Among the most common Hgb abnormalities are the sickle cell disorders, which exhibit a double gene defect that results in the production of hemoglobin S (Hgb S). In Hgb S, the amino acid valine is substituted for glutamine at a critical position on the globin chain, which causes the chains to "lock" when deoxygenated, deforming the erythrocyte into the sickled shape. Repeated sickling damages RBC membranes and shortens the cells' life spans. The abnormally shaped cells pass more sluggishly through the circulation, leading to impaired tissue oxygenation. The gene for Hgb S is most prevalent in black populations and may be present as either sickle cell trait (having one recessive gene for Hgb S) or sickle cell disease (having both recessive genes for Hgb S). and Tests of Hematopoietic Function 27 The Sickledex test, a screening test for sickle cell disorders, detects sickled erythrocytes under conditions of oxygen deprivation. Hemoglobin electrophoresis is necessary, however, to differentiate sickle cell trait (20 to 40 percent Hgb S) from sickle cell disease (70 percent Hgb S). Many other types of abnormal Hgb are caused by defects in globin chain synthesis. Hemoglobin C (Hgb C), for example, has an abnormal amino acid substitution on the chain and can lead to a form of mild hemolytic anemia. Other examples of abnormal Hgb resulting from rearrangement or substitution of the amino acids on the globin chains include hemoglobin E (Hgb E), hemoglobin Lepore (chain abnormalities), and hemoglobin Constant Spring ( -chain abnormality).30 Other disorders involving Hgb pertain to the oxygen-combining ability of the heme portion of the molecule. Examples of types of Hgb associated with such disorders are methemoglobin (Hgb M), sulfhemoglobin, and carboxyhemoglobin. Hgb M is formed when the iron contained in the heme portion of the Hgb molecule is oxidized to a ferric instead of a ferrous form, thus impairing its oxygencombining ability. Methemoglobinemia may be hereditary or acquired. The acquired form may be caused by excessive radiation or by the toxic effects of chemicals and drugs (e.g., nitrates, phenacetin, lidocaine). Note that Hgb F is more easily converted to Hgb M than is Hgb A. Sulfhemoglobin is a pigment that results from Hgb combining with inorganic sulfides. It occurs in those who take sulfonamides or acetanilid. Carboxyhemoglobin results when Hgb is exposed to carbon monoxide. Although this type of Hgb is most commonly seen in individuals with excessive exposure to automobile exhaust fumes, it may also occur in heavy smokers.31 Tests other than Hgb electrophoresis are used to determine the presence of Hgb M and carboxyhemoglobin. INDICATIONS FOR HEMOGLOBIN ELECTROPHORESIS Suspected thalassemia, especially in individuals with positive family history for the disorder Differentiation among the types of thalassemias Evaluation of a positive Sickledex test to differentiate sickle cell trait (20 to 40 percent Hgb S) from sickle cell disease (70 percent Hgb S) Evaluation of hemolytic anemia of unknown etiology Diagnosis of Hgb C anemia Identification of the numerous types of abnormal Hgb, most of which do not produce clinical disease Copyright © 2003 F.A. Davis Company 28 SECTION I—Laboratory Tests Figure 1–5. Formation of manual and abnormal hemoglobin. (From Hillman, RS, and Finch, CA: Red Cell Manual, ed 7. FA Davis, Philadelphia, 1996, with permission.) Reference Values The normal values shown for Hgb electrophoresis are for adults. In newborn infants, 60 to 90 percent of Hgb may consist of Hgb F. This amount decreases to 10 to 20 percent by 6 months of age and to 2 to 4 percent by 1 year. Abnormal forms of Hgb (e.g., Hgb S, Hgb H) are not normally present. Conventional Units SI Units Hgb A 95–97% 0.95 Hgb A2 2–3% 0.02–0.03 Hgb F 1% 0.01 Methemoglobin (Hgb M) 2% or 0.06–0.24 g/dL Sulfhemoglobin Minute amounts Carboxyhemoglobin 0–2.3% 4–5% in smokers Copyright © 2003 F.A. Davis Company CHAPTER 1—Hematology NURSING CARE BEFORE THE PROCEDURE Client preparation is the same as that for any study involving the collection of a peripheral blood sample (see Appendix I). and Tests of Hematopoietic Function 29 The test is performed by exposing RBCs to increasingly dilute saline solutions. The percentage of the solution at which the cells swell and rupture is then noted. THE PROCEDURE Reference Values A venipuncture is performed and the sample collected in a lavender-topped tube. A capillary sample may be obtained in infants and children as well as in adults for whom venipuncture may not be feasible. Normal erythrocytes rupture in saline solutions of 0.30 to 0.45 percent. RBC rupture in solutions of greater than 0.50 percent saline indicates increased fragility. Lack of rupture in solutions of less than 0.30 percent saline indicates decreased RBC fragility. NURSING CARE AFTER THE PROCEDURE Care and assessment after the procedure are the same as for any study involving the collection of a peripheral blood sample (see Appendix I). Complications and precautions: Note and report signs and symptoms associated with the specific type of anemia identified by electrophoresis. Prepare to instruct in therapy and prevention of complications. Offer information about genetic factors and counseling or both, if appropriate. INDICATIONS FOR OSMOTIC FRAGILITY TEST Confirmation of disorders that alter RBC fragility, including hereditary anemias (see Table 1–9) Evaluation of the extent of extrinsic damage to RBCs from burns, inadvertent instillation of hypotonic intravenous fluids, microorganisms, and excessive exercise NURSING CARE BEFORE THE PROCEDURE OSMOTIC FRAGILITY The osmotic fragility test determines the ability of the RCB membrane to resist rupturing in a hypotonic saline solution. Normal disk-shaped cells can imbibe water and swell significantly before membrane capacity is exceeded, but spherocytes (RBCs that lack the normal biconcave shape) and cells with damaged membranes burst in saline solutions only slightly less concentrated than normal saline. Conversely, in thalassemia, sickle cell disease, and other disorders, RBCs are more than normally resistant to osmotic damage (Table 1–9). TABLE 1–9 • Client preparation is the same as that for any study involving the collection of a peripheral blood sample (see Appendix I). THE PROCEDURE A venipuncture is performed and the sample collected in a green-topped tube. A capillary sample may be obtained in infants and children as well as in adults for whom a venipuncture may not be feasible. NURSING CARE AFTER THE PROCEDURE Care and assessment after the procedure are the Causes of Altered Erythrocyte Osmotic Fragility Decreased Fragility Increased Fragility Iron-deficiency anemias Hereditary spherocytosis Hereditary anemias (sickle cell, hemoglobin C, thalassemias) Hemolytic anemias Liver diseases Autoimmune anemias Polycythemia vera Burns Splenectomy Toxins (bacterial, chemical) Obstructive jaundice Hypotonic infusions Transfusion with incompatible blood Mechanical trauma to RBCs (prosthetic heart valves, disseminated intravascular clotting, parasites) Enzyme deficiencies (PK kinase, G-6-PD) Copyright © 2003 F.A. Davis Company 30 SECTION I—Laboratory Tests same as for any study involving the collection of a peripheral blood sample (see Appendix I). Abnormal test results, complications, and precautions: Respond as for any laboratory analysis to determine RBC abnormalities leading to anemia. RED BLOOD CELL ENZYMES To maintain normal shape and flexibility as well as to combine with and release oxygen, RBCs must generate energy. The needed energy is produced almost exclusively through the breakdown of glucose, a process that is catalyzed by a number of enzymes. Deficiencies of these enzymes are associated with hemolytic anemia. Two of the most common deficiencies, both hereditary, involve the RBC enzymes glucose-6-phosphate dehydrogenase and pyruvate kinase. GLUCOSE-6-PHOSPHATE DEHYDROGENASE Glucose-6-phosphate dehydrogenase is an enzyme pivotal in generating the reduced form of nicotinamide adenine dinucleotide phosphate (NADPH) through the pentose pathway in glucose metabolism. More than 100 structural and functional variants of the normal G-6-PD molecule (called type B) have been identified, most of which are clinically insignificant. One variant form (called type A) does, however, produce clinical disease. The type A variant is caused by a sex-linked genetic defect. The abnormal gene is carried by women and is transmitted to men who inherit the disorder. Persons with the type A enzyme (15 percent of blacks) experience no difficulty until challenged by an oxidative stressor, which induces rapid intravascular hemolysis of susceptible cells. Among these stressors are systemic infections, septicemia, metabolic acidosis, and exposure to oxidant drugs (aspirin, chloramphenicol [Chloromycetin], nitrofurantoin [Furadantin], phenacetin, primaquine, probenecid [Benemid], quinidine, quinine, sulfonamides, thiazide diuretics, and tolbutamide [Orinase]). A Mediterranean variant also may occur, especially in individuals of Greek and Italian descent and in some small, inbred Jewish populations. This variant severely reduces enzymatic activity and leads to more severe hemolytic episodes, which are triggered by a greater variety of stimuli and are less likely to be self-limited than in persons with the type A variant. In addition to the oxidative stressors just listed, ingestion of fava beans is known to precipitate hemolytic events in individuals with Mediterraneantype G-6-PD deficiency.32 PYRUVATE KINASE Pyruvate kinase (PK) functions in the formation of pyruvate and adenosine diphosphate (ADP) in glycolysis. The pyruvate thus formed is subsequently converted to lactate. RBCs that lack PK have a low affinity for oxygen. Episodes of hemolysis in individuals lacking this enzyme are severe and chronic and are exacerbated by stressors such as infection. The inherited form of this disorder is transmitted as an autosomal recessive trait; both parents must carry the abnormal gene for the child to be affected. The acquired form of PK deficiency is usually caused by either drug ingestion or metabolic liver disease. INTERFERING FACTORS Young RBCs have higher enzyme levels than do older ones; thus, if the tests are performed within 10 days of a hemolytic episode (when the body is actively replacing lost cells through increased erythropoiesis) or after a recent blood transfusion, the results may be falsely normal. INDICATIONS FOR RED BLOOD CELL ENZYMES STUDY Hemolytic anemia of uncertain etiology, especially when it occurs in infancy or early childhood Reference Values Conventional Units G-6-PD 4.3–11.8 IU/g Hgb 0.28–0.76 mm/mol Hgb 125–281 U/dL packed RBCs (PRBCs) 1.25–2.81 kU/L RBC 6 251–511 U/10 cells 1211–2111 IU/mL PRBCs PK SI Units 2.0–8.8 U/g Hgb 0.3–0.91 mg/dL 0.25–0.51 nU/L RBC Copyright © 2003 F.A. Davis Company CHAPTER 1—Hematology Suspected G-6-PD or PK deficiency, especially in individuals with positive family history or with jaundice occurring in response to stressors, oxidant drugs, or foods such as fava beans NURSING CARE BEFORE THE PROCEDURE Client preparation is the same as that for any study involving the collection of a peripheral blood sample (see Appendix I). THE PROCEDURE A venipuncture is performed and the sample collected in a lavender-topped tube. A capillary sample may be collected in infants and children as well as in adults for whom venipuncture may not be feasible. NURSING CARE AFTER THE PROCEDURE Care and assessment after the procedure are the same as for any study involving the collection of a peripheral blood sample (see Appendix I). Abnormal test results, complications, and precautions: Respond as for any laboratory analysis to determine RBC abnormalities leading to anemia. ERYTHROCYTE SEDIMENTATION RATE The erythrocyte sedimentation rate (ESR or sed rate) measures the rate at which RBCs in anticoaguTABLE 1–10 • and Tests of Hematopoietic Function lated blood settle to the bottom of a calibrated tube. In normal blood, relatively little settling occurs because the gravitational pull on the RBCs is almost balanced by the upward force exerted by the plasma. If plasma is extremely viscous or if cholesterol levels are very high, the upward trend may virtually neutralize the downward pull on the RBCs. In contrast, anything that encourages RBCs to aggregate or stick together increases the rate of settling. Inflammatory and necrotic processes, for example, cause an alteration in blood proteins that results in clumping together of RBCs because of surface attraction. These clumps are called rouleaux. If the proportion of globin to albumin increases or if fibrinogen 3 levels are especially high, rouleaux formation is enhanced and the sed rate increases.33 Specific causes of altered ESRs are presented in Table 1–10. INTERFERING FACTORS Delays in performing the test after the sample is collected may retard the ESR and cause abnormally low results; the test should be performed within 3 hours of collecting the sample. INDICATIONS FOR ERYTHROCYTE SEDIMENTATION RATE TEST Suspected organic disease when symptoms are vague and clinical findings uncertain Causes of Altered Erythrocyte Sedimentation Rates Increased Rate Decreased Rate Pregnancy (uterine and ectopic) Polycythemia vera Toxemia of pregnancy Congestive heart failure Collagen disorders (immune disorders of connective tissue) Sickle cell, Hgb C disease Inflammatory disorders Degenerative joint disease Infections Cryoglobulinemia Acute myocardial infarction Drug toxicity (salicylates, quinine derivatives, adrenal corticosteroids) Most malignancies Drugs (oral contraceptives, dextran, penicillamine, methyldopa, procainamide, theophylline, vitamin A) Severe anemias Myeloproliferative disorders Renal disease (nephritis) Hepatic cirrhosis Thyroid disorders Acute heavy metal poisoning 31 Copyright © 2003 F.A. Davis Company 32 SECTION I—Laboratory Tests Reference Values Normal values for the ESR follow. Note that several laboratory methods can be used to determine the ESR. Values vary according to the method used. Wintrobe (mm/hr) Westergren (mm/hr) Men Cutler (mm/hr) 0–8 50 yr 0–7 0–15 50 yr 5–7 0–20 Women 0–10 50 yr 0–15 0–20 50 yr 25–30 0–30 Landau Micro Method Smith Micro Method Children Newborn–2 yr 1–6 0–1 (newborns) 4–14 yr 1–9 3–13 Identification of the presence of an inflammatory or necrotic process Monitoring response to treatment for various inflammatory disorders (e.g., rheumatoid arthritis, systemic lupus erythematosus) Support for diagnosing disorders associated with altered ESRs (see Table 1–10) increases, note signs of infection or inflammation (pain, temperature) and activity intolerance (fatigue, weakness), and perform activities that conserve the client's energy. Administer ordered anti-inflammatory or antibiotic therapy. As the rate decreases, evaluate for improvement in condition and possible increases in client activity. NURSING CARE BEFORE THE PROCEDURE Client preparation is the same as that for any study involving the collection of a peripheral blood sample (see Appendix I). THE PROCEDURE A venipuncture is performed and the sample collected in a lavender-topped tube. A capillary sample may be obtained in infants and children as well as in adults for whom venipuncture may not be feasible. The sample should be transported promptly to the laboratory, because the test must be performed within 3 hours of collecting the sample. Delays may retard the ESR and cause abnormally low results. NURSING CARE AFTER THE PROCEDURE Care and assessment after the procedure are the same as for any study involving the collection of a peripheral blood sample (see Appendix I). Abnormal values: Note and report increases or decreases in the rate in relation to other test results used to determine the presence of or to monitor the progress of a disease. As the rate LEUKOCYTE STUDIES Leukocytes (white blood cells, WBCs) constitute the body's primary defense against "foreignness"; that is, leukocytes protect the body from foreign organisms, substances, and tissues. The main types of leukocytes are neutrophils, monocytes, eosinophils, basophils, and lymphocytes. All of these cells are produced in the bone marrow. However, lymphocytes may be produced in additional sites. Each of these types of leukocytes has different functions, and each behaves as a related but different system.34 Neutrophils and monocytes, the most mobile and active phagocytic leukocytes, are capable of breaking down various proteins and lipids such as those in bacterial cell membranes. The function of eosinophils is uncertain, although they are believed to detoxify foreign proteins that enter the body through the lungs or intestinal tract. The function of basophils also is not clearly understood, but the cells themselves are known to contain heparin, histamine, and serotonin. Basophils are believed to cause increased blood flow to injured tissues while preventing excessive intravascular clotting. Copyright © 2003 F.A. Davis Company CHAPTER 1—Hematology Lymphocytes play an important role in immunity and may be divided into two main categories, B lymphocytes and T lymphocytes. B lymphocytes are responsible for humoral immunity and antibody production. It is B lymphocytes that ultimately develop into the antibody-producing plasma cells (see Fig. 1–2). T lymphocytes are responsible for cellular immunity and they interact directly with the antigen.35,36 Lymphocytes and related studies are discussed in greater detail in Chapter 3. Note that leukocytes perform their functions outside the vascular bed. Thus, WBCs are merely in transit while in the blood. Because of the many leukocyte functions, alterations in the number and types of cells may be indicative of numerous pathophysiologic problems. WHITE BLOOD CELL COUNT The WBC count determines the number of leukocytes per cubic millimeter of whole blood. The counting is performed very rapidly by electronic devices. The WBC may be performed as part of a CBC, alone, or with differential WBC count. An elevated WBC count is termed leukocytosis; a decreased count, leukopenia. In addition to the normal physiological variations in WBC count, many pathological problems may result in an abnormal WBC count (see Table 1–2). If the WBC count is low, a buffy coat smear can be performed to identify leukemia or solid tumor cells in the blood. An alteration in total WBC count indicates the degree of response to a pathological process but is not specifically diagnostic for any one disorder. A more complete evaluation is obtained through the differential WBC count. INDICATIONS FOR A WHITE BLOOD CELL COUNT Routine screening as part of a CBC Suspected inflammatory or infectious process (see Table 1–2) and Tests