Hepatitis C

This is a test to determine if you have contracted the hepatitis C virus (HCV) and to monitor treatment of the infection. Hepatitis C is a virus that can infect and damage the liver. Hepatitis C antibody is produced in the body in response to exposure to the hepatitis C virus (HCV). The most common test for HCV looks for these antibodies in your blood. Other tests detect the presence of viral RNA, the amount of viral RNA present, or determine the specific subtype of virus. Hepatitis C often leads to chronic hepatitis, which can progress to cirrhosis and liver cancer (hepatocellular carcinoma). Early detection of the virus can alert your doctor to follow your liver function more closely than usual and to consider treating you if you are chronically infected.

Anti-HCV tests detect the presence of antibodies to the virus, indicating exposure to HCV. These tests cannot tell if you still have an active viral infection, only that you were exposed to the virus in the past. Usually, the test is reported as "positive" or "negative." There is some evidence that, if your test is "weakly positive," it may not mean that you have been exposed to the HCV virus. The Centers for Disease Control and Prevention (CDC) revised its guidelines in 2003 and suggests that weakly positive tests be confirmed with the next test before being reported.

HCV RIBA test is an additional test to confirm the presence of antibodies to the virus. In most cases, it can tell if the positive anti-HCV test was due to exposure to HCV (positive RIBA) or represents a false signal (negative RIBA). In a few cases, the results cannot answer this question (indeterminate RIBA). Like the anti-HCV test, the RIBA test cannot tell if you are currently infected, only that you have been exposed to the virus.

HCV-RNA test identifies whether the virus is in your blood, indicating that you have an active infection with HCV. In the past, it was usually performed by a test called a qualitative HCV. Qualitative HCV RNA is reported as a "positive" or "detected" if any HCV viral RNA is found; otherwise, the report will be "negative" or "not detected". The test may also be used after treatment to see if the virus has been eliminated from the body.

Viral Load or Quantitative HCV tests measure the number of viral RNA particles in your blood. Viral load tests are often used before and during treatment to help determine response to treatment by comparing the amount of virus before and after treatment (usually after 3 months); successful treatment causes a decrease of 99% or more (2 logs) in viral load soon after starting treatment (as early as 4-12 weeks), and usually leads to viral load being not detected. Some newer viral load tests can detect very low amounts of viral RNA, and some laboratories no longer do qualitative HCV RNA tests if they use one of these versions of viral load testing.

Viral genotyping is used to determine the kind, or genotype, of the virus present. There are 6 major types of HCV; the most common (genotype 1) is less likely to respond to treatment than genotypes 2 or 3 and usually requires longer therapy (48 weeks, versus 24 weeks for genotype 2 or 3). Genotyping is often ordered before treatment is started to give an idea of the likelihood of success and how long treatment may be needed.

PREPARATION FOR TEST

A blood sample is obtained by inserting a needle into a vein in the arm.

NORMAL FINDINGS

This test is normally negative.

Ranges for normal findings may vary among different laboratories and hospitals. You should always check with your doctor after having lab work or other tests done to discuss the meaning of your test results and whether your values are considered within normal limits.

MEANING OF TEST

Your caregiver will go over the test results with you and discuss the importance and meaning of your results, as well as treatment options and the need for additional tests if necessary.

OBTAINING THE TEST RESULTS

It is your responsibility to obtain your test results. Ask the lab or department performing the test when and how you will get your results.