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HIV Viral Load

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Also known as: HIV Nucleic Acid Amplification Test; HIV NAAT; HIV NAT; HIV PCR; Quantitative Plasma RNA Test; HIV Quantification
Formal name: Human Immunodeficiency Virus RNA, Quantitative
Related tests: CD4 and CD8; HIV Antibody; HIV Proviral DNA; p24 Antigen; HIV Drug Resistance (Genotypic and Phenotypic)

The Test Sample

What is being tested?

Human immunodeficiency virus (HIV) is the virus that causes acquired immunodeficiency syndrome (AIDS). This test measures the amount (viral load) of HIV nucleic acid (RNA) in the blood. 

When a person is initially infected with HIV, the virus replicates — it produces more and more copies of itself — and moves into the lymph nodes, spleen, and other parts of the body. In the early stages of infection, there may not be any noticeable signs or symptoms of disease or only flu-like symptoms, although the virus is usually present in high amounts. Even when there are no symptoms, the virus continues to replicate and to damage or kill immune cells.

About 3-8 weeks (rarely, up to six months) after initial exposure to the virus, the person's immune system begins to produce HIV antibodies in response to the infection and suppresses the HIV viral load, decreasing it to a low level. Initial symptoms typically resolve, but the infection does not go away.

An HIV infection may simmer quietly for a decade or more, slowly degrading the immune system. Eventually, the immune system is so weakened that the disease begins to affect the body's ability to fight infections and certain cancers. Symptoms of AIDS begin to appear at this stage as the body becomes more susceptible to infections with microorganisms such as tuberculosis and fungi or other diseases such as Kaposi's sarcoma. The person's HIV viral load also begins to increase.

Treatments for AIDS are initiated to suppress the amount of HIV virus present in the blood and limit its ability to replicate, slowing the progression of the disease. If a person with AIDS discontinues treatment or if it loses its efficacy, then the person's HIV viral load again begins to increase.

The HIV RNA test detects HIV virus genetic material and measures how many copies of HIV (viral load) are present in the blood at a particular time. It can track increases and decreases in HIV viral load and, in conjunction with a CD4 count, be used to evaluate disease activity and treatment effectiveness.


How is the sample collected for testing?

A blood sample is drawn by needle from a vein in the arm.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.