Viral Load Measurement
A viral load test measures how much
human immunodeficiency virus (HIV) is in the blood.
Viral load is first measured when you are diagnosed with HIV infection. This
initial measurement serves as the baseline, and future viral load measurements
will be compared with the baseline. Since viral load can vary from day to day,
the trend over time is used to determine if the infection is getting worse. If
your viral load shows a steady increase over several measurements, it means the
infection is getting worse. If the trend in viral load decreases over several
measurements, it means that the infection is being suppressed.
viral load is measured using one of three different types of tests:
- Reverse-transcriptase polymerase chain reaction
- Branched DNA (bDNA) test
- Nucleic acid
sequence-based amplification (NASBA) test
These tests measure the amount of the genetic material
(RNA) of HIV in the blood. But each test reports the
results differently, so it is important to use the same test over time.
Why It Is Done
A viral load measurement test is done
- Monitor changes in the HIV
- Guide treatment choices.
- Monitor how well
treatment is working.
You and your doctor may set up a different schedule
for the test, but the most common schedule is the following:
- If you are not receiving
antiretroviral therapy (ART), your
viral load should be measured every 3 to 4 months.
- If you
are receiving antiretroviral therapy:
- A viral load measurement is taken before
you start treatment. This is your baseline measurement.
viral load measurement is taken 4 to 8 weeks after you start treatment to
determine your response to the medicines. When you start treatment or switch
to new medicines, some decrease in your viral load is
- If the expected decrease in viral load occurs and your
CD4+ cell count remains stable, your viral load will
be measured every 3 to 6 months. The CD4+ count monitors how well your
immune system is working.
Your doctor may consider your viral load measurement along
with your CD4+ count to decide when to start antiretroviral therapy.