| Monitoring Your Immune System
We've come a long way since having HIV meant just waiting around
to get sick, fearing that every little cough or sniffle was the
beginning of the end. While monitoring your symptoms is important,
new tests, and a new understanding of how HIV illness progresses,
can give you a sense of how healthy your immune system is and help
you make decisions about when or whether
to start taking drugs to fight the virus.
If you know the Immune
Basics, you know that HIV infects CD4 cells, which then produce
more HIV and die off. Two measurements, then, are crucial to monitoring
your CD4 cell count.
CD4 Cell Test
Also known as T4 tests or T-cell counts, the CD4 Cell test measures
the number of CD4 cells in your blood. If you just found out you
have HIV, you should get two T-cell counts, spaced two or three
weeks apart, to see how many CD4 cells you have. Why two tests rather
than one? Because the number of CD4 cells can vary depending on
how much sleep you got, what time of day you were tested, whether
or not you have a cold or other illness, and other factors. After
the initial two tests, it's a good idea to get periodic CD4 tests
to get a sense of how much damage HIV is doing to your immune system.
People with more than 350 CD4 cells should repeat the test every
three to six months. People with fewer than 350 T-cells should test
every three to four months. If you've just started anti-HIV treatment,
get a CD4 test beforehand, one a month afterward, and then another
in three months. Getting blood drawn at the same time of day, and
using the same lab, can help you compare results more accurately
over time.
The lower your CD4 cells, the more likely you are to get sick.
Most healthy people have a range of somewhere between 800 and 1,200
T-cells per cubic milliliter of blood, though, again, it varies.
Having below 200 CD4 cells gives you an official AIDS diagnosis
and puts you at risk of the AIDS-related pneumonia known as Pneumocystis
carinii pneumonia (PCP). Having below 100 CD4s means even greater
vulnerability to a number of other infections.
It's also useful to look at what percentage of your T-cells are
CD4 cells and what percent are CD8 cells. Thirty-five percent CD4
is relatively normal, but 20% can be a sign that your immune system
has been weakened.
Viral Load Test
This test -- which measures how much HIV is in your blood -- is
also very important to figuring out how much damage HIV is doing
to your immune system and whether you might want to consider drugs
to help suppress the virus. There are two different kinds of viral
load tests in common use - the branched DNA (bDNA) and the Polymerase
Chain Reaction (PCR) test. Results, or counts, from the PCR test
are approximately twice that of the bDNA, but that has to do with
the test’s methodology, not the total level of virus in your body.
The higher the number of "copies" of the HIV virus in each cubic
centimeter of blood, the more likely disease progression is, although
this can vary from person to person. As with CD4 cell counts, if
you've just been diagnosed you should have two viral load tests
spaced two to four weeks apart. The average of these two tests is
considered your "baseline." Get another viral load test every three
months after that. If you decide to start anti-HIV treatment, get
a test immediately beforehand, another four weeks after starting
the drugs, and then every one to three months, so you can monitor
whether the drugs are working.
We don't know how high a viral level can go. Over a million copies
is not uncommon. Between 5,000 and 30,000 is generally considered
to be low to average, 30,000 to 50,000 is average to high, 50,000
to 100,000 is high, and over 100,000 is very high. Some tests can
detect a lower number of copies than others. Typically, tests can
detect down to either 400 or 50 copies, but some experimental tests
can detect even fewer copies. If you're body is responding to treatment
you probably need the ultra sensitive (down to 50 copies) test.
If you change doctors, see if your new one can use the same lab
as the old one did to help with continuity of results.
Monitoring Your Symptoms
Variations in CD4 counts and viral load are frequent; therefore
it’s the pattern of the variation, rather than individual test results
that is most important. Equally important, however, is paying close
attention to how you feel. How are you sleeping and eating? How
is your digestion? Do you have any infections? Have you experienced
diarrhea, weight loss, or weight gain? People in the earlier stages
of HIV disease will often develop physical symptoms such as skin
rashes, fevers, night sweats, diarrhea, and lack of energy. These
symptoms aren't considered serious enough to be classified as AIDS,
but they may indicate that the HIV virus is multiplying in your
body.. Even if something's unrelated or seems small, get it treated,
since you want to minimize any additional stress on your immune
system. You also want to begin establishing a
relationship with your doctor. It’s best to find out how you
work together before you experience a major illness.
Tests for Those Going on Medication, or for Those Whose
Medication is not Working
Two tests called genotypic and phenotypic
resistance tests — can hold very important information about which
HIV drugs to start with or which ones to switch to if your current
medication is failing. When HIV replicates it often makes mistakes,
which results in somewhat different strains of the virus. Some of
these strains can be resistant to HIV medications. These tests determine
if you are infected with any drug resistant copies of the HIV virus.
Even if you've never taken an anti-HIV drug, you may have gotten
infected with a virus that's already resistant to some drugs.
The phenotypic test takes a sample of the virus from your blood
and "challenges" it with each of the available anti-HIV drugs. If
HIV grows in spite of the drug, that drug is probably not useful
to you.
The genotypic test takes a sample of the virus, looks at its genetic
sequence, and tries to match that with the genetic sequences of
common mutated viruses known to be resistant to different drugs.
Before these tests, patients on failing drug combinations wouldn't
know which drug or combination of drugs weren't working, forcing
them to stop all treatment. Now, doctors are better able to pinpoint
and discontinue the ineffective drugs while leaving the others in
place.
Neither test is foolproof. Both require a detectable viral load,
usually between 500 and 1000 copies. They are much better at predicting
which drugs won't work rather than which drugs will work. Genotype
tests are less expensive, usually around $300-500 and have a shorter
turn-around time, usually 1-2 weeks. Phenotype tests may cost as
much as $800-1000 and take longer to report, usually 2-3 weeks.
Most insurers, including Medicaid and ADAP Plus now pay for resistance
tests, though the number of tests you can receive per year may be
limited.
© 2003 Gay Men's Health Crisis |
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