Blood work:
Two common tests to use for
monitoring HIV disease

January 2008     View PDF     En español

Interpreting test results

Results from viral load tests can be difficult to understand. Some general guidelines can be found below. As with CD4 cell counts, the trend of viral loads over time is the most important and not an individual result. Both the size (how large a change) and duration (how long it lasts: week, month, year) of changes in HIV levels are important in assessing these results. Some guidelines to use include:

• Viral load below 10,000 copies/ml is generally considered “low.”
• Viral load above 100,000 copies/ml is generally considered “high.”
• Low, stable and decreasing viral load is considered a good thing.
• High or increasing viral load calls for attention as it may point to the failure of a regimen.

The minimum reliable change in a viral load test is a three-fold change, or a 1/2 log. This means three times larger or smaller than the last test result. Thus, a change from 20,000 down to 10,000 (two-fold) would not be deemed significant. One would want to see a ten-fold (1 log) or more decrease in HIV levels when starting a new anti-HIV regimen. (For more information on “logs,” read Project Inform’s publication, Blood work: A complete guide for monitoring HIV.

People with “undetectable” viral load should remember that it does not mean that their HIV is gone. What it does mean is that it’s simply present in an amount below what the test can measure. For example, if the level of sensitivity of the test that you have done is 50 and you have fewer than 50 copies of HIV in your blood sample, then your viral load is said to be undetectable. HIV may actually be there, but just in too small of a quantity for the test to detect