CD4 Lymphocyte Count
Reviewed
A CD4 count is a blood test that measures the number of CD4 cells (helper T cells) in your blood. It is mainly used to check the health of your immune system if you are infected with HIV. It helps see how HIV is affecting your immune system, monitor your risk for infections, check how well HIV treatment is working, and help diagnose AIDS. It may also be used to monitor treatment after an organ transplant, help diagnose lymphoma, or diagnose DiGeorge syndrome.
Preparation and collection
No special preparation needed.
Understanding this test
Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.
- Results may vary by age, other health conditions, and medicines you take.
- Labs may use different reference ranges.
- A single abnormal result is not diagnostic; trends over time are more meaningful.
What to do next
If you have HIV, regular CD4 counts and viral load tests help monitor treatment. If your CD4 count continues to decrease, your provider may change your medicine or start preventive treatment for opportunistic infections.