blood disorders
Lymphocytopenia
Diagnosis of Lymphocytopenia
Complete blood count Mild lymphocytopenia is usually diagnosed by chance when a complete blood count is done for other reasons. Complete blood count testing also is done in people with recurrent or severe infections and in people with infections caused by organisms that do not usually cause infections. Such testing may show severe lymphocytopenia as an explanation for why the person has developed recurrent or unusual infections. When the numbers of lymphocytes are drastically reduced, doctors usually do a blood test for human immunodeficiency virus (HIV) and other infections and sometimes take a sample of bone marrow to examine under a microscope ( Bone Marrow Examination ). The number of specific types of lymphocytes (T cells, B cells, and NK cells) in the blood can also be determined. A decrease in certain types of lymphocytes may help doctors diagnose some disorders, such as AIDS or certain hereditary immunodeficiency disorders. 