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Viral Load Measurement

What To Think About

  • The results from the different methods (RT-PCR, bDNA, NASBA) to measure viral load are not interchangeable. This makes it important to use the same method of measuring each time.
  • An undetectable viral load result does not mean that you no longer have HIV in your blood. It simply means that the amount of HIV in the blood was too low for the test to detect. HIV still can be passed to another person even when the viral load cannot be detected.
  • The viral load test is not used routinely to diagnose HIV. The HIV antibody test is used for this purpose. To learn more, see the topic Human Immunodeficiency Virus (HIV) Test.
  • The viral load test is more accurate than a CD4+ count to evaluate the activity of HIV. The CD4+ count measures how well your immune system is working and may be used to determine when to start antiretroviral therapy. The viral load test is used to determine the response to antiretroviral therapy. No HIV should be detected in the blood of people whose treatment is successful. To learn more about the CD4+ count, see the topic CD4+ Count.

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.

ByHealthwise Staff
Primary Medical ReviewerE. Gregory Thompson, MD - Internal Medicine
Specialist Medical ReviewerPeter Shalit, MD, PhD - Internal Medicine
Last RevisedOctober 22, 2012
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WebMD Medical Reference from Healthwise

Last Updated: October 22, 2012
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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