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.
CD4+ cell ranges
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.
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.
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
"Guide to Opportunistic Infections". Regardless of CD4+ cell count, yearly
monitoring for tuberculosis is becoming increasingly important.
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