CD4 Lymphocyte Count Test
A CD4 count measures the number of CD4 cells in your blood. These cells help your immune system fight infections. The test is mainly used to check the health of your immune system if you have HIV.
What this test measures
A CD4 count measures the number of CD4 cells (a type of white blood cell) in a sample of your blood. These cells help trigger your immune system to destroy viruses, bacteria, and other germs.
What your results mean
Reference ranges vary by laboratory and by your age and sex. MedlinePlus does not publish a single normal range for this test — always read your result against the range printed on your own lab report and discuss it with your provider.
Higher-than-normal results
Counts above the normal range may be a sign of an infection or a blood cancer.
Lower-than-normal results
A low CD4 count (below 500) means HIV has weakened your immune system. If you don't have HIV, a low count may be caused by an infection, chemotherapy, or medicines that weaken the immune system.
Frequently asked questions
What is a CD4 count?
A CD4 count is a blood test that measures the number of CD4 cells in your blood. These cells help your immune system fight infections.
Why is a CD4 count used for HIV?
HIV attacks and destroys CD4 cells. The test helps see how HIV is affecting your immune system and how well treatment is working.
What is a normal CD4 count?
For healthy adults and teens, a normal CD4 count is 500 to 1,200 cells per cubic millimeter. But ranges may vary by lab.
What does a low CD4 count mean?
A low CD4 count (below 500) means your immune system is weakened. If you have HIV, a count of 200 or fewer means you have AIDS.
Can a CD4 count be used for other conditions?
Yes, it can help monitor treatment after an organ transplant, help diagnose certain lymphomas, and help diagnose DiGeorge syndrome.
Related lab tests
Sources
- MedlinePlus: CD4 Lymphocyte Count — NIH MedlinePlus
Last updated . Information is aggregated from official public sources and is not a substitute for professional medical care.