From the Guidelines
The primary laboratory test ordered to screen for hepatitis C infection is the anti-HCV antibody test. This blood test detects antibodies that the body produces in response to HCV infection, which usually develop 2 to 6 months after exposure, during the acute phase of infection, and persist throughout life 1.
Key Points to Consider
- A positive anti-HCV antibody test result indicates the patient has active HCV infection, has had a past infection that has resolved, or the result is a false positive 1.
- A positive anti-HCV antibody result should be followed by a quantitative nucleic acid test for HCV RNA to confirm active infection 1.
- The HCV RNA test can first be detected at 1 to 3 weeks after exposure and indicates active infection 1.
Screening Recommendations
- The anti-HCV antibody test is recommended as the initial screening test because it is less expensive and easier to perform than RNA testing.
- Early detection of hepatitis C is crucial because the infection can be asymptomatic for decades while causing progressive liver damage, and current direct-acting antiviral treatments can cure over 95% of infections.
Important Considerations
- The recombinant immunoblot assay is no longer available or recommended for HCV screening 1.
- If a patient who had a negative test result for HCV RNA within the past 6 months is newly found to be viremic, acute HCV infection is confirmed 1.
From the Research
Laboratory Tests for Hepatitis C Infection
The laboratory tests used to screen for hepatitis C infection include:
- Enzyme-linked immunosorbent assay (ELISA) 2, 3
- Chemiluminescence immunoassay (CLIA) 4, 5
- Electrochemiluminescence immunoassay (ECLIA) 6
- Chemiluminescent microparticle immunoassay (CMIA) 6
- Recombinant immunoblot assay (RIBA) 4, 2, 5
- Reverse transcriptase polymerase chain reaction (RT-PCR) 4, 2, 3
- Nucleic acid amplification tests (NAT) 3
Screening and Diagnostic Tests
The initial screening test for hepatitis C infection is typically an enzyme-linked immunosorbent assay (ELISA) or a chemiluminescence immunoassay (CLIA) 2, 3. If the result is reactive, a confirmatory test such as RT-PCR or NAT is performed to detect the presence of HCV-RNA 4, 3.
Test Performance
The performance of these tests varies, with some having higher sensitivity and specificity than others 5, 6. For example, the light-initiated chemiluminescent assay (LiCA) has been shown to have high sensitivity and specificity for detecting HCV antibody 5. Similarly, ECLIA and CMIA have been found to be highly sensitive and specific for detecting anti-HCV antibodies 6. However, all of these tests can produce false-positive results, highlighting the need for confirmatory testing 4, 6.