CD4 + Testing

For many years, testing the number of CD4+ cells was the most common way to measure the effects of HIV disease. Low numbers of these cells (below 200) accurately predicts the risk of major infections. The meaning of test results in between this critical level of 200 and the normal level of 1,000 is unclear. Physicians once typically started treatment for people when the CD4+ was below 500, but this was always an arbitrary number simply selected from clinical trials. By itself, this number doesn't tell us enough about the state of disease. It only shows that the level of CD4+ cells is below normal, to varying degrees. Getting the full picture of HIV disease requires additional tests, especially the Viral Load Test.

High range:
In general, a CD4+ count above 500 suggests no immediate danger, even though it may represent a loss of half the normal CD4+ cell count (1,000). The 500 level is sometimes cited as the bottom of the "normal" range, but this can be misleading. While an occasional drop to 500 may be normal, a steady or falling count of 500 or even 600 is not normal and indicates suppressed immunity. At the very least, dietary counseling, nutritional supplements, CD4+ cell monitoring, and periodic use of other tests are recommended in this range, whether or not treatments are used.

Medium range:
CD4+ counts in this range indicate significant decline of the immune system. However, serious symptoms are uncommon in this range. Some researchers believe this is the optimum time to begin treatment, especially if the viral load test also indicates significant viral activity.

Low range:
CD4+ counts below 300 indicate the greatest risk of infections and according to the 1993 definition of AIDS, a CD4+ count of 200 or less constitutes an AIDS diagnosis. A person with counts below 300 CD4+ may remain stable for many years, especially with careful health management. While some people have warning signs in the form of symptoms before major infections occur, this is not always the case. Some progress directly from apparent health to serious OIs.

It has become common to put people with CD4+ counts below 200 or 300 on preventive treatment against PCP (for example, Bactrim/Septra), along with all people who have already suffered an initial bout of pneumocystis. Prevention strategies for all of the common opportunistic infections are described in the Project Inform "Guide to Opportunistic Infections". Regardless of CD4+ cell count, yearly monitoring for tuberculosis is becoming increasingly important.

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