As part of your HIV care, your provider will order several laboratory tests. The results of these lab tests, along with your physical exam and other information you provide, will help you and our staff to work together to develop the best plan to manage your HIV care so that you can get the virus under control, protect your health, and reduce the chance that you will pass the virus to others. Your healthcare provider will repeat some of these tests as part of your ongoing HIV care to continue to assess your health and how well your HIV treatment is working.
The lab tests may include:
CD4 count: CD4 cells are a type of white blood cell. They are specialized cells of the immune system that are destroyed by HIV. A CD4 count measures how many CD4 cells are in your blood. The higher your CD4 cell count, the healthier your immune system. The CD4 count of an uninfected adult/adolescent who is generally in good health ranges from 500 cells/mm3 to 1,600 cells/mm3. In contrast, if HIV has destroyed so many CD4 cells that you have a CD4 count of fewer than 200/mm3, you are considered to have progressed to stage 3 (AIDS), the most advanced stage of HIV infection.
Why it’s important: A CD4 count is a good measure of your risk of opportunistic infections and an indicator of how well your immune system is working. Treatment with antiretroviral therapy (ART), medications that control the HIV, is recommended for everyone with HIV, no matter how high or low their CD4 count is. However, a low CD4 count (below 200/mm3) increases the urgency to start ART.
CD4 Percentage: This measures how many of your white blood cells are actually CD4 cells. This measurement is more stable than CD4 counts over a long period of time, but, for most people, the CD4 count remains a more reliable measure of how well your immune system is working than the CD4 percentage.
Why it’s important: This measurement is less likely to vary in between blood tests than CD4 counts (which can vary from month to month or day to day).
Viral Load (VL): An HIV viral load test, also called an HIV RNA test, tracks how many HIV particles are in a sample of your blood. This is called your viral load. Why it’s important: A goal of HIV treatment is to keep your viral load so low that the virus can’t be detected by a viral load test. It’s important to get a viral load test to see the level of HIV in your blood before starting treatment and help guide the choice of HIV medications and then to get repeat tests to track your response to HIV treatment. Complete Blood Count (CBC): This is a measure of the concentration of red blood cells, white blood cells, and platelets in a sample of your blood.
Why it’s important: A CBC is one of the most commonly ordered blood tests. It can reveal infections, anemia (abnormality in your red blood cells), and other medical issues. Drug Resistance Tests: HIV can change form, making it resistant to some HIV medicines. A drug resistance test helps your provider identify which, if any, HIV medicines will not be effective against the strain of HIV you have.
Why it’s important: Drug resistance test results help your provider determine which HIV medicines are most likely to work for you.
Pregnancy Test: This test shows whether a woman is pregnant or not. Why it’s important: If you are pregnant, you can greatly lower your risk of passing HIV to your baby and protect your own health by taking ART during pregnancy, labor, and delivery. You and your health care provider can discuss steps you can take prevent transmitting HIV to your baby.