The viral load of hepatitis C refers to the amount of virus present in the bloodstream. The quantitative HCV RNA tests measure the amount of hepatitis C virus in the blood. The result will be an exact number, such as "1,215,422 IU/L." Many people refer to the quantitative measurement as the hepatitis C "viral load."

Viral load tests are used to confirm active hepatitis C infection and are used during treatment to help determine response. If you have lower levels of virus in your blood when you start treatment, you may have a better chance of getting rid of the virus.

Explanation of test results:

There are 2 situations in which a quantitative test is useful:

The quantitative HCV RNA test is checked before a patient starts treatment.

For each patient, the result can be described as either a "high" viral load, which is usually >800,000 IU/L, or a "low" viral load, which is usually <800,000 IU/L. It's not uncommon to have a viral load in the millions. Today's hepatitis C treatments are very effective with both high and low viral loads. An undetectable HCV viral load 10-12 weeks after hepatitis C is completed is associated with a cure.

The quantitative HCV RNA test is used to monitor a patient who is currently on treatment.

The response to treatment is considered good when the quantitative HCV RNA measurement drops and the virus eventually becomes completely undetectable.

Other things to know:

• The viral load measurement does not tell us anything about the severity of a patient's liver disease or the degree of fibrosis (scarring). For that information, the patient would need additional testing.
• It is not necessary to check the viral load repeatedly during treatment.
• If a quantitative HCV RNA result is reported as "<15 IU/L," this means that the quantitative test cannot measure the hepatitis C virus. It may mean that there is no detectable HCV RNA at all, but it may mean that the level of virus is just too low for the test to pick it up.