CD4 Lymphocyte Count
Reviewed
Also called: CD4 lymphocyte count, CD4+ count, T4 count, T-helper cell count, CD4 percent
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.
Specimen: Blood
Why this test may be ordered
- To see how HIV is affecting your immune system.
- To monitor your risk for developing opportunistic infections or certain cancers.
- To help check how well HIV treatment is working (used with an HIV viral load test).
- To help check the stage of HIV and diagnose AIDS.
- To monitor treatment after an organ transplant (low CD4 means the anti-rejection medicine is working).
Preparation and collection
No special preparation needed.
Blood sample from a vein in your arm
There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
Understanding results
CD4 count results are usually given as a number of cells per cubic millimeter of blood. Your healthcare provider will interpret your results in the context of your overall health, HIV status, and other test results. What is normal for you depends on your age, other health conditions, and the medicines you take. Your provider will look at several test results over time to see trends.
- Normal CD4 count: Your immune system is functioning normally, and if you have HIV, your treatment is likely working well. Limitation: Normal for healthy adults and teens: 500 to 1,200 cells per cubic millimeter. This indicates a healthy immune system. Next step: If you have HIV, continue your treatment as prescribed. Your provider will monitor your CD4 count and viral load regularly.
- Low CD4 count: Your immune system is weakened and you may be at increased risk for infections. If you have HIV and your count is 200 or fewer, you have AIDS. Limitation: Low CD4 count (below 500 cells per cubic millimeter). If you have HIV, a low count means HIV has weakened your immune system. A count of 200 or fewer means you have AIDS, with high risk of life-threatening infections or cancers. If you do not have HIV, a low count may be due to infection, chemotherapy, or medicines that weaken the immune system. Next step: If you have HIV, your provider may change your HIV medicines or start preventive treatment for opportunistic infections. It is important to take your medicines as prescribed and get regular follow-up tests.
- High CD4 count: Your immune system may be responding to an infection or there may be an underlying condition such as lymphoma. Limitation: High CD4 count (above normal range). May be a sign of an infection or a blood cancer. Next step: Your provider will likely recommend additional tests to determine the cause of the high count.
- 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.
- Why is this test being done?
- What is my current CD4 count and what does it mean for my immune system?
- How often should I repeat this test?
- Do I need any other tests, such as an HIV viral load test?