The U.S. Department of Health and Human Services considers a normal level to be 500 to 1000 thymus-derived lymphocytes, or T-cells, per cubic millimeter of blood, according to Healthline. Different labs use different measurement ranges, reports MedlinePlus. Doctors can discuss specific laboratory ranges and test results with their patients.
Doctors use the T-cell count blood test diagnostically when patients have symptoms of a weak immune system and to monitor conditions like HIV infection and AIDS, notes Healthline. Medications can affect the accuracy of the test, so patients should discuss using corticosteroids, immunosuppressants, anti-rejection, chemotherapy and radiation drugs, supplements, and other medications with their doctors. A doctor may advise the patient to reduce the dosage or refrain from taking the medication prior to the test. Patients should also discuss recent surgery or significantly stressful experiences with their doctors, because they can also affect the results of the test.
Low T-cell counts can result from aging, viral infections, congenital T-cell deficiency, radiation exposure and cancers of the blood and lymphatic systems as well as immunodeficiency disorders, including DiGeorge syndrome, Job syndrome, HIV and AIDS, explains Healthline. Less commonly, high T-cell counts can result from infectious mononucleosis, multiple myeloma and acute lymphocytic leukemia.