Viral Load Measurement

HIV Load Measurement, Viral Load Assay

Test Overview

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:

• Reverse-transcriptase polymerase chain reaction (RT-PCR) test
• 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. However, each test reports the results differently, so it is important to use the same test over time.

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Author:	Douglas Dana Maria G. Essig, MS, ELS	Last Updated: May 24, 2007
Medical Review:	Anne C. Poinier, MD - Internal Medicine E. Gregory Thompson, MD - Internal Medicine W. David Colby IV, MSc, MD, FRCPC - Infectious Disease Peter Shalit, MD, PhD - Internal Medicine
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