for Veterans and the Public
Understanding laboratory tests
Laboratory tests can help keep tabs on your health. Some of these tests will be done soon after you learn you are HIV positive. Then depending on your immune status, whether you are on medication or not, and a variety of other factors, your provider will set up a schedule for you.
The lab tests look at:
- how well your immune system is functioning (CD4 count)
- how rapidly HIV is replicating, or multiplying (viral load)
- how well your body is functioning (tests look at your kidneys, liver, cholesterol, and blood cells)
- whether you have other diseases that are associated with HIV (tests for certain infections)
When done shortly after you find out you have HIV, these tests establish a starting point or "baseline." Future tests will let you know how far from this baseline you have moved. This can help you tell how fast or slow the disease is moving and indicate whether treatments are working.
Most labs include a "normal" range (high and low values) when they report test results. The most important results are the ones that fall outside these normal ranges. Test results often go up and down over time so don't worry about small changes. Instead look for overall trends.
What follows are descriptions of the most common tests: