CD4 Cell Count (Per Microliter)

This test measures the number of CD4 cells in a sample of your blood, and it is usually done to check how well your immune system is working. It is most often used to monitor HIV infection, but your provider may also order it to evaluate other conditions or medicines, such as drugs taken after an organ transplant, that can weaken your body's natural defenses.

Doctors may order a CD4 cell count to evaluate your immune system’s health, especially if you have HIV, have had organ transplants, or are undergoing treatments that weaken the immune system. It’s also used to monitor immune recovery during treatment.

Your result shows how many CD4 cells are present in a given amount of blood. A higher count generally means your immune system is stronger, while a lower count suggests it is weakened. If you are living with HIV, your care team uses this number to see how the condition is progressing and whether your current treatment plan is working well over time.

A lower CD4 count may indicate a weakened immune system, which can increase your risk of infections or other health problems. Higher counts suggest a stronger immune response. Your doctor will interpret results in the context of your overall health and medical history.

This test is performed with a simple blood draw, usually at a lab or clinic. A health professional cleans a small patch of skin, often on the inside of your elbow, wraps a band around your upper arm, and uses a thin needle to collect blood into a tube. The process takes only a few minutes and may cause brief, mild discomfort or slight bruising afterward.

A small blood sample is taken from a vein in your arm. The blood is then analyzed in a lab to count the number of CD4 cells. This test is quick and usually done in a doctor’s office or lab.

For most healthy adults, a typical CD4 count falls between about 500 and 1,200 cells/mm³, although exact ranges vary slightly from one laboratory to another. A count below 200 cells/mm³ is considered a sign of serious immune suppression and is one criterion used to diagnose AIDS in people with HIV. Your provider will interpret your result using the reference range printed on your report.

There is no single reference range that applies to everyone. Results are compared to your baseline or to your doctor’s expectations based on your health status, treatment, and other factors.