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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.
The viral load is measured using one of three different types of tests:
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.
A viral load measurement test is done to:
You and your doctor may set up a different schedule for the test, but the most common schedule is the following:
Your doctor may consider your viral load measurement along with your CD4+ count to decide when to start antiretroviral therapy.
You do not need to do anything before you have this test.
The health professional drawing blood will:
You may feel nothing at all from the needle puncture, or you may feel a brief sting or pinch as the needle goes through the skin. Some people feel a stinging pain while the needle is in the vein. But many people do not feel any pain (or have only minor discomfort) after the needle is positioned in the vein. The amount of pain you feel depends on the skill of the health professional drawing the blood, the condition of your veins, and your sensitivity to pain.
There is very little risk of complications from having blood drawn from a vein.
A viral load test measures how much human immunodeficiency virus (HIV) is in the blood. The results can take up to 2 weeks.
The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab and depend upon which testing method is used (RT-PCR, bDNA, NASBA). Your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.
Viral load results are reported as the number of HIV copies in a milliliter (copies/mL) of blood. Each virus is called a "copy," because HIV reproduces by making copies of itself (replicating).
HIV is not detected in the blood.
HIV is detected in the blood. Your doctor will compare your current measurement with previous values.
If your viral load increases, it means the infection is getting worse. If the viral load drops, it means that the infection is being suppressed.
Reasons you may not be able to have the test or why the results may not be helpful include:
Other Works Consulted
- Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
- Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.
|Primary Medical Reviewer||E. Gregory Thompson, MD - Internal Medicine|
|Specialist Medical Reviewer||Peter Shalit, MD, PhD - Internal Medicine|
|Last Revised||October 22, 2012|
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