Viral Load Test

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Viral Load Test
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Simply put, a viral load test measures the amount of HIV in your blood. It has become one of the most important tools for doctors and patients when making treatment decisions. While it is sometimes used to determine if antiretroviral therapy should be started—HIV-positive patients with higher viral loads may progress quickly to AIDS without antiretroviral treatment—viral load is most often employed while a person is on therapy to make sure that the medications are working correctly. Generally speaking, if your viral load becomes detectable or continues increasing while you're on treatment, it may be necessary to switch your regimen to control the virus and to protect your CD4 cells and health.

For a complete review of how to use these tests for making treatment decisions, click on the following lesson links:

Lesson When Should I Start Treatment, and What Should I Take First?
When Should I Change My Treatments, and Which Drugs Should I Switch To?

There are actually two types of viral load tests. A viral load report—sent to your doctor after blood samples have been collected and sent to a lab—will specify which test was used. Typically, labs use either the Amplicor polymerase chain reaction (PCR) test, or either the Quantiplex or Versant branched DNA (bDNA) tests. Sorry for the mouth full—you really don't need to remember these long names. Just look for "PCR" or "bDNA" on your lab results, and you'll know which one was used.

Each test uses a different technique to measure the amount of virus, but their results tell you the same thing—the amount of HIV in your blood. It's important to use just one of these tests over time, and not switch between the two. PCR values are approximately twice those measured by bDNA (i.e., 20,000 copies using PCR is equal to 10,000 copies using bDNA).

There is no "normal" amount of HIV, since it is not normally present in the body. Your viral load lab report will list the lowest amount of virus that the particular test can detect. For example, the first version of Amplicor PCR cannot accurately detect less than 400 copies of the virus in a milliliter of blood. If HIV can be detected, the results of the lab report will include the number of HIV copies found (e.g., 10,000 copies/mL). The second version of Amplicor PCR is more sensitive, but still cannot accurately detect less than 50 copies of the virus in your blood. Most commercially available versions of viral load tests measure down to between 40 and 75 copies of virus accurately.

While taking therapy, your viral load lab report might show that HIV can no longer be detected. This is known as having an "undetectable" viral load. However, this does not mean that HIV is no longer present in your body since less than 5% of HIV in the body can be found in the blood. It is also important to keep in mind that even the newest versions of PCR and bDNA cannot detect very small amounts of HIV that may be present in the blood. But, in terms of figuring out how to treat HIV based on these results, the goal is simple: to keep the amount of HIV in your blood as low as possible.

What does a viral load test look like?

Your viral load test results might be grouped with your other lab results, but you'll usually see it printed on its own page. Look for a "Test Name" that includes "HIV", and this will usually be what you're looking for.

See below for what a typical viral load test looks like. Click on a test name in the left column to view an explanation of its significance & meaning. (note: to see and/or print a complete list of test name explanations, click here.)

Clinical Laboratory Report
  Patient Name Date Drawn Date Received Date of Report
    DOE, JOHN     12/20/2009     12/20/2009       12/22/2009  
 
  Sex Age Client Name / Address I.D. Number Account Number
    M     31     MEDICAL CENTER
  YOUR DOCTOR, M.D.
  123 MAIN STREET
  ANYTOWN     US        10023
    78987654     12343  
   
  Ordering Physician   Time
Drawn
 
    SMITH
  123094567
    Specimen Number  
        918273     11:00    
  Patient I.D./Soc. Sec Number
 
 
TEST NAME RESULT UNITS REFERENCE RANGE
 
HIV-1 RNA, PCR, 2ND GEN
HIV-1 RNA, PCR 885        H Copies/mL < 50
LOG COPIES/ML 2 .95  H Log CPS/mL < 1.7
 

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Last Revised: November 29, 2010

This content is written by the POZ and AIDSmeds editorial team. For more information, please visit our "About Us" page.

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