You’re always hearing that your CD4 count measures how well your immune
system is doing with HIV. But there’s another measurement to consider:
the CD4 “percentage.” This number tells you what percentage of your
lymphocytes (infection- and cancer-fighting white blood cells) is made
up of CD4s. The percentage tends to be more stable than the CD4
count—which can drop during short-term events like a yeast infection, a
vaccine or serious stress. As long as the percentage is safe, temporary
dips in count shouldn’t cause alarm. Here’s how four HIV docs surveyed
by POZ use CD4 percentages in decision-making:
STARTING MEDS:
All say CD4 percentage, CD4 count and viral load should be considered.
Many docs suggest starting meds—if a patient is ready to handle
them—after repeated CD4 counts below 300 to 350. As for percentage, a
recent study suggests that people with HIV are at risk for illness if
it dips below 17%. “If this appears on two or three reports, I strongly
recommend starting meds” regardless of CD4 count, says New York City’s
Lloyd Bailey, MD. Antonio Urbina, MD, also a New Yorker, and Chicago’s
Beverly Sha, MD, start at 14%. Lisa Sterman, MD, of San Francisco,
doesn’t look for a set CD4 count or percentage, because she finds that
each patient has a variety of numbers and health characteristics to
consider. “And for women, who tend to have lower CD4 counts,” Sterman
says, “percentages are more important.”
SWITCHING COMBOS: For
Sha and Sterman, changes in viral load, not CD4s, suggest regimen
changes. Urbina adds, “If CD4 count and percentage drop, I look for a
hidden infection like TB or syphilis [to explain the drop], rather than
switching.”
STARTING PREVENTIVE MEDS: As the immune
system deteriorates, people with HIV become vulnerable to opportunistic
infections like pneumocystis carinii pneumonia (PCP). Prophylactic
(preventive) treatments are available. Federal guidelines (and most
AIDS docs) call for starting PCP prophylaxis at CD4 counts below 200 or
CD4 percentages below 14. Preventive treatments for other infections
are recommended only at lower CD4 counts.
