T-cell count
Thymus derived lymphocyte count; T-lymphocyte count; T cell countA T-cell count measures the number of T cells in the blood. Your health care provider may order this test if you have signs of a weak immune system, such as due to having HIV/AIDS.
HIV/AIDS
Human immunodeficiency virus (HIV) is the virus that causes acquired immunodeficiency syndrome (AIDS). When a person becomes infected with HIV, the ...
How the Test is Performed
Blood sample is needed
Venipuncture is the collection of blood from a vein. It is most often done for laboratory testing.
How to Prepare for the Test
No special preparation is necessary.
How the Test will Feel
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.
Why the Test is Performed
T cells are a type of lymphocyte. Lymphocytes are a type of white blood cell. They make up part of the immune system. T cells help the body fight diseases or harmful substances, such as bacteria or viruses.
Your health care provider may order this test if you have signs of a weak immune system (immunodeficiency disorder). It may also be ordered if you have a disease of the lymph nodes. Lymph nodes are small glands that make some types of white blood cells. The test is also used to monitor how well treatment for these types of diseases is working.
Immunodeficiency disorder
Immunodeficiency disorders occur when the body's immune response is reduced or absent.
One type of T cell is the CD4 cell, or "helper cell." People with HIV/AIDS have routine T-cell tests to check their CD4 cell counts. The results help your provider monitor the disease and its treatment.
Normal Results
Normal results vary depending on the type of T-cell tested.
In adults, a normal CD4 cell count ranges from 500 to 1,500 cells/mm3 (0.50 to 1.50 cells/109/L).
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your provider about the meaning of your specific test results.
What Abnormal Results Mean
Higher than normal T-cell levels may be due to:
- Cancer, such as acute lymphocytic leukemia or multiple myeloma
Acute lymphocytic leukemia
Acute lymphoblastic leukemia (ALL) is a fast-growing cancer of a type of white blood cells called lymphocytes. ALL occurs when the bone marrow produ...
ImageRead Article Now Book Mark ArticleMultiple myeloma
Multiple myeloma is a blood cancer that starts in the plasma cells in the bone marrow. Bone marrow is the soft, spongy tissue found inside most bone...
ImageRead Article Now Book Mark Article - Infections, such as hepatitis or mononucleosis
Hepatitis
Hepatitis is swelling and inflammation of the liver.
ImageRead Article Now Book Mark ArticleMononucleosis
Mononucleosis, or mono, is a viral infection that causes fever, sore throat, and swollen lymph glands, most often in the neck.
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Lower than normal T-cell levels may be due to:
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Acute viral infections
Acute
Acute means sudden. Acute symptoms appear, change, or worsen rapidly. It is the opposite of chronic.
ImageRead Article Now Book Mark Article - Aging
- Cancer
- Immune system diseases, such as HIV/AIDS
HIV/AIDS
Human immunodeficiency virus (HIV) is the virus that causes acquired immunodeficiency syndrome (AIDS). When a person becomes infected with HIV, the ...
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Radiation therapy
Radiation therapy
Radiation therapy uses high-powered radiation (such as x-rays or gamma rays), particles, or radioactive seeds to kill cancer cells.
ImageRead Article Now Book Mark Article - Steroid treatment
Risks
There is very little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
- Excessive bleeding
- Fainting or feeling lightheaded
- Blood accumulating under the skin (hematoma)
- Infection (a slight risk any time the skin is broken)
- Multiple punctures to locate veins
This test is often performed on people with a weakened immune system. Therefore, the risk for infection may be higher than when blood is drawn from a person with a healthy immune system.
References
Berliner N. Leukocytosis and leukopenia. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 153.
Holland SM, Gallin JI. Evaluation of the patient with suspected immunodeficiency. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 12.
McPherson RA, Massey HD. Overview of the immune system and immunologic disorders. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 44.
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Blood test - illustration
Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. Preparation may vary depending on the specific test.
Blood test
illustration
-
Blood test - illustration
Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. Preparation may vary depending on the specific test.
Blood test
illustration
Review Date: 8/20/2023
Reviewed By: Jacob Berman, MD, MPH, Clinical Assistant Professor of Medicine, Division of General Internal Medicine, University of Washington School of Medicine, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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