immune disorders
Overview of Immunodeficiency Disorders
Diagnosis of Immunodeficiency Disorders
Blood tests Skin tests A biopsy Sometimes genetic testing Doctors must first suspect that an immunodeficiency exists. Then they do tests to identify the specific immune system abnormality. Doctors suspect immunodeficiency when one or more of the following occur: A person has many recurrent infections (typically sinusitis, bronchitis, middle ear infections, or pneumonia). Infections are severe or unusual. A severe infection is caused by an organism that normally does not cause severe infection (such asPneumocystis, fungi, or cytomegalovirus). Recurring infections do not respond to treatment. Family members also have frequent and severe recurring infections. To help identify the type of immunodeficiency disorder, doctors ask at what age the person began to have recurring or unusual infections or other characteristic symptoms. Different types of immunodeficiency disorders are more likely depending on the age at which infections starts, as in the following: Younger than 6 months: Usually an abnormality in T cells Age 6 to 12 months: Possibly a problem with both B cells and T cells or with B cells Older than 12 months: Usually an abnormality in B cells and antibody production The type of infection may also help doctors identify the type of immunodeficiency disorder. For example, knowing which organ (ear, lungs, brain, or bladder) is affected, what the infecting organism is (bacteria, fungus, or virus), and what the organism's species is can help. Doctors ask the person about risk factors, such as diabetes, use of certain drugs, exposure to toxic substances such as certain pesticides or benzene, and the possibility of having close relatives with immunodeficiency disorders (family history). The person may also be asked about past and current sexual activity, use of intravenous drugs, and previous blood transfusions to determine whether Human Immunodeficiency Virus (HIV) Infection could be the cause. Results of a physical examination may suggest immunodeficiency and sometimes the type of immunodeficiency disorder. For example, doctors suspect certain types of immunodeficiency disorders when the following are found: The spleen is enlarged. There are problems with the lymph nodes and tonsils. In some types of immunodeficiency disorders, the lymph nodes are extremely small. In some other types, lymph nodes and tonsils are swollen and tender. Laboratory tests are needed to confirm the diagnosis of immunodeficiency and to identify the type of immunodeficiency disorder. including a Complete blood count (CBC), are done. CBC can detect abnormalities in blood cells that are characteristic of specific immunodeficiency disorders. A blood sample is taken and analyzed to determine the total number of white blood cells and the percentages of each main type of white blood cell. The white blood cells are examined under a microscope for abnormalities. Doctors also determine immunoglobulin levels and the levels of certain specific antibodies produced after the person is given vaccines. If any results are abnormal, additional tests are usually done. Skin testsmay be done if the immunodeficiency is thought to be due to a T-cell abnormality. The skin test resembles the tuberculin skin test, which is used to screen for tuberculosis. Small amounts of proteins from common infectious organisms such as yeast are injected under the skin. If a reaction (redness, warmth, and swelling) occurs within 48 hours, the T cells are functioning normally. No reaction could suggest a T-cell abnormality. To confirm a T-cell abnormality, doctors do additional blood tests to determine the number of T cells and to evaluate T-cell function. Abiopsymay be done to help doctors identify which specific immunodeficiency disorder is causing the symptoms. For the biopsy, doctors take a sample of tissue from the lymph nodes and/or bone marrow. The sample is tested to determine whether certain immune cells are present. Genetic testingmay be done if doctors suspect a problem with the immune system. The gene mutation or mutations that cause many immunodeficiency disorders have been identified. Thus, genetic testing can sometimes help identify the specific immunodeficiency disorder. If a person has a genetic cause of immunodeficiency, some of their family members also may have the disorder or be carriers of the abnormal gene. Thus, doctors often recommend that close family members be evaluated, sometimes including genetic testing. 