Simple FactSheet: Viral Load Tests

Viral Load Tests
a Simple FactSheet from the AIDS Treatment Data Network

||||| What are viral load tests:

Viral load tests measure what's called HIV RNA. RNA is the part of HIV that knows how to make more virus. There are several different viral load tests. These tests were approved by the FDA for use in checking the health of people with HIV, to see if they may be at risk for getting sick. These tests are also approved for checking the effects of anti-HIV drugs, to see if they are working against the virus.

The results of each of these tests can be a little different, so doctors advise that people stick to the same type of test once they start using viral load testing. In this fact sheet all the viral load numbers from studies are based on what the result would be using the PCR test, as this is the most widely available test at the moment.

||||| How do the tests work:

Scientists have a good idea what some parts of HIV RNA look like. By creating a mirror image and matching it against what they find in someone's blood, they can find HIV RNA. The PCR test encourages the HIV RNA to make more of itself in a laboratory test tube. This makes it easier to measure the amount of HIV RNA that was originally in the blood sample. The bDNA test sets off a chemical reaction with the HIV RNA so it gives out light. Then the amount of light is measured in order to show how much RNA was found.

The results of these tests are usually given as number of HIV RNA copies per milliliter (ml) of blood, like the T4 cell count. The PCR test may give the number of HIV RNA copies per 0.05/ml, so you need to multiply the number by 20 to get the standard result. Results are also sometimes given as a number x 10³, which means you have to add three zeros to the number - e.g. 40 x 10³ is 40,000. This can get really confusing, so make sure you and your doctor are certain you are reading a viral load test result correctly before making any treatment decisions.

||||| What do the numbers mean:

Early viral load results from two large studies of a drug called delavirdine have recently been released. These studies found that the viral load test was a very good marker of disease progression. In these studies of around 1,700 people, viral load was better than CD4 cell counts at showing whether someone might be at risk for getting sicker.

People who began the studies with a viral load of less than 20,000 had only a 1% chance of experiencing any disease progression during the approximately 60 weeks for which information has been collected. People who started with a viral load of between 20,000 and 200,000 had a slightly higher chance of disease progression. People who started with a viral load of over 200,000 had a 24% chance of disease progression.

Treatment that reduced viral load was linked to improved health. Improved health was most noticeable in people who started the studies with a viral load of over 20,000. For these people, a reduction in viral load of 70% or more for as little as 8 weeks reduced their chance of experiencing any disease progression by half during the study period of a little over a year.

||||| What's the goal of anti-HIV treatment:

Recent studies of triple combinations of anti-HIV drugs have shown that it is possible to reduce the levels of HIV in the blood to levels too low for the PCR test to measure. The original PCR test could not find less than 400 copies of HIV RNA in a blood sample, but a new PCR viral load test is now available that can measure down to 50 copies of HIV RNA. This new test is called the "ultra-sensitive" PCR test. New guidelines from the Public Health Service state that the goal of anti-HIV treatment is to keep viral load as low as possible for as long as possible, ideally below the limit of what the viral load test can find.

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 in circulating blood. The rest is in your 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 is ongoing. Also, measuring the good effect an HIV treatment has on the viral load doesn't take into account any bad side-effects the treatment might have on the body. Further research will hopefully give people a clearer idea of how best to use viral load tests

Viral load testing is typically covered by public and private insurance, including Medicaid . All types of viral load tests have been given a standard reimbursement code known as an HCPCS code. The HCPCS number is G0100, and this may be helpful to know if your provider is unsure of the correct reimbursement code.

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\|\|\|\|\| What are viral load tests:
Viral load tests measure what's called HIV RNA. RNA is the part of HIV that knows how to make more virus. There are several different viral load tests. These tests were approved by the FDA for use in checking the health of people with HIV, to see if they may be at risk for getting sick. These tests are also approved for checking the effects of anti-HIV drugs, to see if they are working against the virus. The results of each of these tests can be a little different, so doctors advise that people stick to the same type of test once they start using viral load testing. In this fact sheet all the viral load numbers from studies are based on what the result would be using the PCR test, as this is the most widely available test at the moment.
\|\|\|\|\| How do the tests work:
Scientists have a good idea what some parts of HIV RNA look like. By creating a mirror image and matching it against what they find in someone's blood, they can find HIV RNA. The PCR test encourages the HIV RNA to make more of itself in a laboratory test tube. This makes it easier to measure the amount of HIV RNA that was originally in the blood sample. The bDNA test sets off a chemical reaction with the HIV RNA so it gives out light. Then the amount of light is measured in order to show how much RNA was found. The results of these tests are usually given as number of HIV RNA copies per milliliter (ml) of blood, like the T4 cell count. The PCR test may give the number of HIV RNA copies per 0.05/ml, so you need to multiply the number by 20 to get the standard result. Results are also sometimes given as a number x 10³, which means you have to add three zeros to the number - e.g. 40 x 10³ is 40,000. This can get really confusing, so make sure you and your doctor are certain you are reading a viral load test result correctly before making any treatment decisions.
\|\|\|\|\| What do the numbers mean:
Early viral load results from two large studies of a drug called delavirdine have recently been released. These studies found that the viral load test was a very good marker of disease progression. In these studies of around 1,700 people, viral load was better than CD4 cell counts at showing whether someone might be at risk for getting sicker. People who began the studies with a viral load of less than 20,000 had only a 1% chance of experiencing any disease progression during the approximately 60 weeks for which information has been collected. People who started with a viral load of between 20,000 and 200,000 had a slightly higher chance of disease progression. People who started with a viral load of over 200,000 had a 24% chance of disease progression. Treatment that reduced viral load was linked to improved health. Improved health was most noticeable in people who started the studies with a viral load of over 20,000. For these people, a reduction in viral load of 70% or more for as little as 8 weeks reduced their chance of experiencing any disease progression by half during the study period of a little over a year.
\|\|\|\|\| What's the goal of anti-HIV treatment:
Recent studies of triple combinations of anti-HIV drugs have shown that it is possible to reduce the levels of HIV in the blood to levels too low for the PCR test to measure. The original PCR test could not find less than 400 copies of HIV RNA in a blood sample, but a new PCR viral load test is now available that can measure down to 50 copies of HIV RNA. This new test is called the "ultra-sensitive" PCR test. New guidelines from the Public Health Service state that the goal of anti-HIV treatment is to keep viral load as low as possible for as long as possible, ideally below the limit of what the viral load test can find. 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 in circulating blood. The rest is in your 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 is ongoing. Also, measuring the good effect an HIV treatment has on the viral load doesn't take into account any bad side-effects the treatment might have on the body. Further research will hopefully give people a clearer idea of how best to use viral load tests Viral load testing is typically covered by public and private insurance, including Medicaid . All types of viral load tests have been given a standard reimbursement code known as an HCPCS code. The HCPCS number is G0100, and this may be helpful to know if your provider is unsure of the correct reimbursement code.