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Myths and realities of starting HIV treatment
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What Your Lab Tests Mean

Lab tests

Regular visits to your healthcare provider for blood tests or lab work are an important part of taking charge of your health. Blood tests and lab work can show what the HIV virus is doing inside your body. And they provide a starting point to compare to your future test results. If you are on meds these tests can show how well the meds are working against the HIV virus.

Certain lab tests can help you and your healthcare provider:

  • Decide when to start HIV treatment
  • Determine how well your meds are working
  • Decide which HIV meds are best for you

One of the tests

There are two key lab tests used to measure HIV activity as well as show how well your HIV meds are working against the HIV virus. These are the viral load test and the CD4 (T-cell) cell count test.

Viral load test: This measures the amount of HIV virus in a sample of blood. You want this number to be as low as possible. If you're on HIV meds the viral load test shows how well they are controlling the virus. When the amount of virus in your blood becomes so low that the viral load test cannot measure it, your viral load is said to be "undetectable." This doesn't mean that you are cured. It means that the ability for the HIV virus to make copies of itself has been slowed.

A person with HIV can have a viral load from less than 50 copies to over 1,000,000 copies of the virus per milliliter of blood (copies/mL). Depending on which test is used, either less than 400 or less than 50 copies of the virus per milliliter is said to be undetectable.

Viral load levels

CD4 cell count: This measures how many infection-fighting cells (also called T-helper cells or T-cells) are in a sample of blood. It is a way to track how well your immune system is working. HIV treatment should increase your CD4 (T-cell) count or at least keep it from going down.

CD4 (T-cell) cell counts above 500 cells/mm3 are said to be normal. Department of Health and Human Services (DHHS) treatment guidelines advise starting HIV meds when the CD4 (T-cell) count is 500 cells/mm3 or less. A CD4 (T-cell) count below 200 cells/mm3 means that the immune system is very weak; it is also one of the ways to tell that someone with HIV has AIDS.

T-cell count

The following test is used to decide which HIV meds have the best chance of working for you. It is helpful before you start or change meds:

Drug resistance test: This determines which meds may work and which meds won’t work against your HIV virus. If a certain HIV drug does not work against your HIV virus, the virus is said to be "resistant" to that drug. When the HIV virus is resistant to a certain HIV med, the virus can make copies of itself even though you take the drug. Drug resistance can occur two ways. You may be infected with a drug-resistant strain of HIV. Or the strain of HIV you have may suddenly change, which is called a mutation. It is critical that you take your meds every day exactly as prescribed. This is referred to as treatment adherence and it is key to decreasing drug resistance. Based on the results of your drug resistance tests, your healthcare provider can choose meds that have a good chance of working against your exact virus.

To learn more about understanding your lab tests, talk to your healthcare provider.

Next: Goals of HIV Treatment