A CD4 count is a test that measures the number of CD4 cells in your blood. CD4 cells, also known as T cells, are white blood cells that fight infection and play an important role in your immune system. A CD4 count is used to check the health of the immune system in people infected with HIV (human immunodeficiency virus).
HIV attacks and destroys CD4 cells. If too many CD4 cells are lost, your immune system will have trouble fighting off infections. A CD4 count can help your health care provider find out if you are at risk for serious complications from HIV. The test can also check to see how well HIV medicines are working.
Other names: CD4 lymphocyte count CD4+ count, T4 count, T-helper cell count, CD4 percent
A CD4 count may be used to:
You may also need a CD4 count if you’ve had an organ transplant. Organ transplant patients take special medicines to make sure the immune system won’t attack the new organ. For these patients, a low CD4 count is good, and means the medicine is working.
Your health care provider may order a CD4 count when you are first diagnosed with HIV. You will probably be tested again every few months to see if your counts have changed since your first test. If you are being treated for HIV, your health care provider may order regular CD4 counts to see how well your medicines are working.
Your provider may include other tests with your CD4 count, including:
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.
You don’t need any special preparations for a CD4 count.
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.
CD4 results are given as a number of cells per cubic millimeter of blood. Below is a list of typical results. Your results may vary depending on your health and even the lab used for testing. If you have questions about your results, talk to your health care provider.
While there is no cure for HIV, there are different medicines you can take to protect your immune system and can prevent you from getting AIDS. Today, people with HIV are living longer, with a better quality of life than ever before. If you are living with HIV, it’s important to see your health care provider regularly.