HIV Viral Load

This test detects and/or measures the amount (viral load) of RNA (nucleic acid) of the human immunodeficiency virus (HIV) in blood. It is the virus that causes acquired immunodeficiency syndrome (AIDS). When a person is 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. Eventually, the immune system is so weakened that the disease begins to affect the body’s ability to fight infections and certain cancers. More symptoms 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.

About 3-8 weeks (rarely up to six months) after exposure to the virus, the body begins to produce HIV antibodies in response to the infection. These antibodies can be detected with a screening test to determine if you have been infected with HIV. However, if your exposure occurred within the last few weeks, the level of antibody may not be high enough to be detected. It is in this “window period” of more recent exposure that the virus may be detectable with an HIV RNA test (viral load) to determine your HIV status. Because the level of technology and resources needed to perform this test are high, it is not as widely available as the antibody test and is used infrequently for diagnosis. Occasionally, a p24 antigen test is used to detect early infection with HIV.

As HIV progresses, the virus continues to replicate and the number of copies of virus, the “viral load,” in the blood increases. If you have been diagnosed with HIV, the measurement of an HIV viral load (HIV RNA) gives your doctor a general indication of how much HIV is present in the body and how rapidly the virus is replicating. The test can help determine, along with a CD4 count, if and when treatment should be initiated, when to test for drug resistance, or if a different type of treatment protocol is needed. Treatment with anti-viral agents can decrease the viral load in the blood to low or undetectable levels but cannot fully eradicate it from the body.

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

No test preparation is needed.