IRIS: A concern for people
starting HIV therapy

April 2008     View PDF     En español

How is it diagnosed?

A differential diagnosis is normally used to identify IRIS. This is when the diagnosis is narrowed down from a list of possibilities until one emerges as the best. A differential diagnosis will consider the failed treatment of the current infection, a possible new infection or malignancy, and drug side effects (especially with hepatitis).

One important thing to consider after starting therapy is the amount of decrease in HIV levels (viral load). IRIS tends to occur when there’s a large drop in HIV levels. An example of this would be going from 100,000 copies of HIV down to about 500, which shows a strong response to therapy but an increased risk for IRIS.

This is another paradox about IRIS, because getting viral load to an undetectable level as soon as possible is one goal of HIV therapy. Should this happen, it’s the most likely time that IRIS will occur. Therefore, closely checking HIV levels is an important way to help diagnose possible IRIS. Other tests can also assist the diagnosis, such as white blood count and C-reactive protein, which indicate inflammation. The higher the levels, the more likely major inflammation is taking place.