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FAQ: What does it mean when different types of blood tests for hepatitis C give different results?

for Veterans and the Public

Frequently Asked Questions

Q: What does it mean when different types of blood tests for hepatitis C give different results?

The first test your doctor probably will perform is called an "antibody" (or anti-HCV) test. A positive result means that you were exposed to the hepatitis C virus at some point in your life.

If the result is positive, your doctor will perform a second test called hepatitis C virus RNA (or HCV RNA) to see if the virus is still in your body. If the RNA test result is positive, then you have chronic hepatitis C infection.

So what does it mean if you have a positive result for the first test but a negative result for the second?

  1. The most likely explanation is that you were infected with hepatitis C but your own immune system fought off the virus. This means you do not have chronic hepatitis C infection, and are not at risk of any medical problems related to hepatitis C.
  2. The second possible explanation is that you were infected with hepatitis C but the amount of virus in your body is too small to be detected by the standard test. If someone had virus that was present but such a low amount that the test wasn't able to detect it, then there could be a "false negative HCV RNA" test. But the newest techniques used by labs for HCV RNA are extremely sensitive and can detect as few as 12 copies of the virus (12 IU/mL). So, this scenario is possible where you could have a false negative test, but it is unlikely.
  3. The third possible explanation is that your first test results (from the HCV antibody test) are incorrect, and you weren't infected with hepatitis C in the first place. This would be a "false positive antibody" test. This error doesn't happen very often, but it's possible. In this situation, you may need a third kind of test, called HCV RIBA test--the RIBA test is to confirm the antibody as a true positive or a true negative. If the RIBA test is positive then you truly have HCV antibody. If the RIBA test is negative, then you do not have HCV antibody even if the antibody test itself was positive. A negative result means you were never infected with hepatitis C at all.