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T-cell count
Thymus derived lymphocyte count; T-lymphocyte count; T cell count
A T-cell count measures the number of T cells in the blood. Your doctor may order this test if you have signs of a weak immune system, such as due to having HIV/AIDS.
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 white blood cells. 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 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 regular T-cell tests to check their CD4 cell counts. The results help the provider monitor the disease and its treatment.
HIV/AIDS
Human immunodeficiency virus (HIV) is the virus that causes AIDS. When a person becomes infected with HIV, the virus attacks and weakens the immune ...
Normal Results
Normal results vary depending on the type of T-cell tested.
In adults, a normal CD4 cell count ranges from 500 to 1,200 cells/mm 3 .
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 cell called a lymphoblast. ALL occurs when the bone marrow prod...
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...
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Infections, such as hepatitis or
mononucleosis
Mononucleosis
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:
-
Acute
viral infections
Acute
Acute means sudden or severe. Acute symptoms appear, change, or worsen rapidly. It is the opposite of chronic.
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- Cancer
- Immune system diseases, such as HIV/AIDS
-
Radiation therapy
Radiation therapy
Radiation therapy uses high-powered x-rays, particles, or radioactive seeds to kill cancer cells.
ImageRead Article Now Book Mark Article - Steroid treatment
Risks
Risks associated with having blood drawn are slight:
- Excessive bleeding
- Fainting or feeling lightheaded
- Hematoma (blood accumulating under the skin)
- 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, Schafer AI, eds. Goldman's Cecil Medicine . 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 167.
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 . 8th ed. Philadelphia, PA: Elsevier Saunders; 2015: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 . 22nd ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 43.
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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: 8/29/2015
Reviewed By: Laura J. Martin, MD, MPH, ABIM Board Certified in Internal Medicine and Hospice and Palliative Medicine, Atlanta, GA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
