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 in a sample of your blood.
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
You don't need any special preparations for a CD4 count.
A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.
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 results are usually given as a number of cells per cubic millimeter of blood. But labs may have different ways of describing "normal" CD4 counts.
- Normal: 500 to 1,200 cells per cubic millimeter: Normal CD4 count for healthy adults and teens: 500 to 1,200 cells per cubic millimeter Limitation: What's normal for you depends on your age, other health conditions, and the medicines you may take. Next step: That's why it's important to talk with your provider about what your test results mean.
- Low: below 500 cells per cubic millimeter: If you have HIV, a low CD4 count means that HIV has weakened your immune system. Limitation: If you don't have HIV, a low CD4 count may be caused by an infection. Cancer chemotherapy and medicines that weaken your immune system may also cause low CD4 counts. Next step: If your CD4 count continues to decrease for many months, your provider may change your medicine and also may start preventive treatment for opportunistic infections.
- 200 or fewer cells per cubic millimeter: A CD4 count of 200 or fewer cells per cubic millimeter means that you have AIDS. With AIDS you have a high risk of developing life-threatening infections or cancers. Limitation: CD4 counts may change even when your health has not changed. Next step: If you're diagnosed with HIV, it's important to start treatment as soon as possible.
- High: above the normal range: Counts above the normal range may be a sign of an infection or a blood cancer. Limitation: So, your provider will usually look at a few test results over time to see if there's a trend in your CD4 counts. Next step: That's why it's important to talk with your provider about what your test results mean.
- 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 are living with HIV, it's important to take your medicine as prescribed and get regular blood tests, including CD4 counts.
- 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?
Evidence source
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.