What is the initial test for diagnosing Hepatitis C (HCV)?

Initial Testing for Hepatitis C Virus (HCV) Infection

The initial test for diagnosing Hepatitis C (HCV) infection is an anti-HCV antibody test, which should be used as the first-line diagnostic test for HCV screening. 1

Diagnostic Algorithm for HCV Testing

Step 1: Initial Screening

• Anti-HCV antibody testing using an FDA-approved assay (laboratory-based or point-of-care) is the recommended initial test for HCV screening 1
• Both laboratory-based enzyme immunoassays (EIA) and rapid point-of-care tests like OraQuick HCV Rapid Antibody Test can be used with similar sensitivity and specificity 1

Step 2: Follow-up Testing Based on Initial Results

• If anti-HCV antibody test is negative:

  • No further testing is needed for most individuals 1
  • For persons with recent exposure (within past 6 months) or who are immunocompromised, HCV RNA testing or follow-up antibody testing is recommended 1

• If anti-HCV antibody test is positive:

  • Reflex HCV RNA testing should be performed to confirm active infection 1
  • Ideally, the same blood sample should be used for reflex testing to avoid requiring patients to return for a second blood draw 1

Interpretation of Test Results

• Positive anti-HCV antibody + Positive HCV RNA: Indicates current (active) HCV infection requiring medical evaluation and potential treatment 1
• Positive anti-HCV antibody + Negative HCV RNA: Indicates either past resolved infection or false positive antibody test 1
• Negative anti-HCV antibody: Generally indicates absence of HCV infection 1

Special Testing Considerations

• For suspected acute hepatitis C or in immunocompromised patients, HCV RNA testing should be included in the initial evaluation 1
• For persons at risk of reinfection after previous viral clearance, HCV RNA testing is recommended as the primary test since antibody tests will remain positive 1
• Anti-HCV positive but HCV RNA negative individuals should be retested for HCV RNA 3 months later to confirm a recovered infection 1

Additional Testing After Confirmed HCV Infection

• Quantitative HCV RNA testing is recommended prior to treatment initiation to establish baseline viral load 1
• HCV genotype testing may be considered when it could alter treatment recommendations 1

Clinical Pearls and Pitfalls

• Anti-HCV antibodies persist after viral clearance (spontaneous or treatment-induced), so antibody testing alone cannot distinguish between current and resolved infection 1
• False negative antibody results can occur during early acute infection (first 4-10 weeks) and in severely immunocompromised patients 1
• Reflex HCV RNA testing significantly improves the continuum of care by eliminating the need for a return visit, which is a major barrier to diagnosis and treatment 1
• Supplemental antibody testing (using a different assay) can be considered to distinguish between true positivity and biologic false positivity when HCV RNA is negative 1