HIV Viral Load
At a Glance
Why Get Tested?
To monitor the status of HIV disease in conjunction with other lab tests and physical disease progression and to guide therapy. Your viral load levels are usually used as an indicator of how well your immune system is dealing with HIV. If you are on anti-HIV treatments, it can be an indictor of how well the treatments are working.
When to Get Tested?
When first diagnosed with HIV, every 4 weeks at the start of therapy, and every 3-4 months during long-term therapy, or as your doctor recommends
Sample Required?
A blood sample taken from a vein in your arm
Test Preparation Needed?
No test preparation is needed.
The Test Sample
What is being tested?
This test measures the amount of HIV in your blood. 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.
There is still concern that there is a lot of virus in other places in the body, not just the blood - only 2% of HIV is circulating in the blood, the rest is in the lymph system and other body tissue . Early results indicate that changes in viral load in the blood are mirrored in the lymph system, but research into this is continuing. "Viral load" means the number of HIV particles or copies of the virus present in the blood.
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.
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.
How is the sample collected for testing?
A blood sample is taken by needle from a vein 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.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
The Test
How is it used?
The viral load test is quantitative measurement of HIV nucleic acid (RNA) that provides important information that is used in conjunction with the CD4 cell count:
- to monitor the status of HIV disease,
- to guide recommendations for therapy, and
- to predict the future course of HIV.
Evidence shows that keeping the viral load levels as low as possible for as long as possible decreases the complications of HIV disease and prolongs life.
Public health guidelines state that treatment should be considered for asymptomatic HIV-infected people who have viral loads higher than 30,000 copies per milliliter of blood using a test known as a branched DNA test, or more than 55,000 copies using an RT-PCR test.
There are several methods for testing viral load; results are not interchangeable so it is important that the same method be used each time.
When is it requested?
A viral load test is requested, usually in conjunction with a CD count, when a patient is first diagnosed with HIV. The test result functions as a baseline measurement that shows how actively the virus is reproducing and whether treatment is immediately necessary.
If and when therapy is started, your doctor may request a viral load test and a CD4 count about every four weeks to evaluate whether therapy is being effective. To monitor long-term therapy, your doctor will request viral load tests and CD4 counts about every four months.
What does the test result mean?
HIV viral load tests are reported as the number of HIV copies in a milliliter (copies/mL) of blood. If the viral load measurement is high, it indicates that HIV is reproducing and that the disease will likely progress faster than if the viral load is low. A high viral load can be anywhere from 5,000 to 10,000 copies/mL and can range as high as one million or more copies/mL.
A low viral load is usually between 200 to 500 copies/mL, depending on the type of test used. This result indicates that HIV is not actively reproducing and that the risk of disease progression is low.
A viral load result that reads “undetectable” does not mean that you are cured. It may mean that either the HIV RNA is not present in your blood at the time of testing or that the level of HIV virus in your blood is below the threshold needed for detection by this test. Other tests that are ultra-sensitive and that can measure as few as 20 to 40 copies in a milliliter of blood can be performed to make sure.
If you are not taking your medication as your physician has directed, your viral load may not drop as significantly as if you take your medication on time.
Change in viral load is also a very important measurement. A rising count indicates an infection that is getting worse, while a falling count indicates improvement and suppression of the HIV infection.
A non-infected person should have no circulating HIV virus in his or her blood and, therefore, a negative or undetectable viral load.
Is there anything else I should know?
Viral load testing should not be used for diagnosing HIV; the HIV antibody test is still the preferred method of choice for this.
Viral load testing done by the PCR method is incredibly sensitive, which can give rise to false-positive results.
Common Questions
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Article Sources
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.
