What labs should be checked to screen for hepatitis?

Laboratory Tests for Screening Hepatitis

For comprehensive hepatitis screening, order HBsAg for hepatitis B and anti-HCV antibody with reflex HCV RNA testing for hepatitis C as the primary screening tests. 1, 2

Hepatitis B Screening Tests

• HBsAg (hepatitis B surface antigen) is the primary marker for detecting current HBV infection, with positivity for >6 months defining chronic infection 1
• Total anti-HBc (hepatitis B core antibody) indicates current or previous HBV infection 1
• Anti-HBs (hepatitis B surface antibody) indicates recovery from infection or successful vaccination 1
• For patients with positive HBsAg, additional testing should include:
  • HBeAg and anti-HBe to assess viral replication 1
  • HBV DNA quantification to determine viral load 1
  • ALT/AST to assess liver inflammation 1

Hepatitis C Screening Tests

• Anti-HCV antibody test with reflex HCV RNA testing is the recommended initial screening approach 2
• The reflex testing approach requires only a single blood collection, eliminating the need for a return visit for confirmatory testing 2
• A positive antibody test with positive RNA indicates current (active) HCV infection 2
• A positive antibody test with negative RNA suggests past resolved infection or false positive 2

Additional Testing for Comprehensive Evaluation

• Liver function tests should be ordered to assess liver disease severity:

  • ALT/AST (aminotransferases) 1
  • Alkaline phosphatase and gamma-glutamyl transpeptidase 1
  • Bilirubin, albumin, and prothrombin time/INR to evaluate liver function 1

• Tests for coinfections should be considered:

  • Anti-HDV in patients with a history of injection drug use or from endemic areas 1
  • Anti-HIV in high-risk groups 1
  • Anti-HAV IgG to determine immunity status to hepatitis A 1

Interpretation of Common Serologic Patterns for Hepatitis B

• Acute HBV infection: HBsAg positive, IgM anti-HBc positive 1
• Chronic HBV infection: HBsAg positive for >6 months, total anti-HBc positive, IgM anti-HBc negative 1
• Past HBV infection with immunity: HBsAg negative, anti-HBs positive, total anti-HBc positive 1
• Vaccine-induced immunity: HBsAg negative, anti-HBs positive, total anti-HBc negative 1

Common Pitfalls to Avoid

• Relying solely on HBsAg for HBV screening may miss occult HBV infections, especially in immunocompromised patients 3
• Testing only for anti-HCV without confirmatory HCV RNA testing cannot distinguish between current infection and resolved past infection 2
• Failing to recognize the "window period" when both HBsAg and anti-HBs may be negative (IgM anti-HBc is positive during this period) 1
• For suspected recent exposure to HBV or HCV (within past 6 months), nucleic acid testing (HBV DNA or HCV RNA) is recommended as antibodies may not have developed 3
• For immunocompromised patients, consider direct viral testing (HBV DNA or HCV RNA) as antibody production may be impaired 3