HIV Resistance Testing

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Related tests: HIV viral load

At a Glance

Why Get Tested?

If you have been diagnosed with HIV and are receiving anti-viral therapy that is not working effectively

When to Get Tested?

If your HIV viral load values rise steadily even though you are receiving anti-viral therapy

Sample Required?

A blood sample taken from a vein in your arm

The Test Sample

What is being tested?

In genotypic resistance testing, the genetic code of the particular strain of HIV a patient has is checked to see if there any genetic mutations that are known to cause drug resistance. HIV is said to be resistant to an antiviral medication if it keeps multiplying while a person is taking the drug. Changes (mutations) in the virus cause resistance. HIV mutates almost every time a new copy of the virus is made, but not every mutation causes resistance. Antiviral drugs control most types of HIV, however, a strain of virus containing a mutation that is resistant to a drug will multiply and become the most common form of the virus in the body (as all the other forms are destroyed by the drug). For certain drugs, single mutations of a gene increase resistance to high levels. For other drugs, there are several mutations that are associated with resistance. To avoid the development of antiviral drug resistance, it is usually recommended that you be treated with a combination of drugs that are from two different classes of antiretroviral drugs. This is known as highly active retroviral therapy or HAART.

How is the sample collected for testing?

The test is performed on a sample of blood taken from a needle placed in your 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.

The Test

Common Questions

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Article Sources

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.