There are a few different tests that can diagnose Hepatitis C (or say for sure that a person has the disease). These tests are called HCV antibody, ELISA, Western blot, and quantitative HCV RNA tests. A technique called polymerase chain reaction (PCR) can show that a person has Hepatitis C virus RNA (part of the virus's genetic blueprint) one to two weeks after the person becomes infected. Tests that look for Hepatitis C antibodies (which the body makes to fight the disease) cannot be done this quickly after infection, because the antibodies can take much longer to form and show up.