Tests for Hepatitis A and B Titers
For checking Hepatitis A and B titers, specific serological tests are required to determine immunity status, with IgG anti-HAV for Hepatitis A and HBsAg, anti-HBs, and anti-HBc for Hepatitis B. 1
Hepatitis A Titer Testing
- Test for total (IgG) anti-HAV antibodies to determine immunity to Hepatitis A 1
- A positive IgG anti-HAV result indicates either past infection or successful vaccination 1
- For suspected acute infection, IgM anti-HAV should be ordered (not typically part of routine titer checking) 1
Hepatitis B Titer Testing
Core Testing Panel
- HBsAg (Hepatitis B surface antigen) - indicates current infection 1
- Anti-HBs (Antibody to Hepatitis B surface antigen) - indicates immunity from vaccination or recovery 1
- Anti-HBc (Total antibody to Hepatitis B core antigen) - indicates previous or ongoing infection 1
Additional Tests When Indicated
- IgM anti-HBc - helps distinguish acute from chronic infection (positive in acute infection) 1, 2
- HBeAg and anti-HBe - markers of viral replication and infectivity 1
- HBV DNA - quantitative test to measure viral load 1
Interpretation of Hepatitis B Test Results
- Immunity from vaccination: Positive anti-HBs, negative anti-HBc, negative HBsAg 1
- Immunity from past infection: Positive anti-HBs, positive anti-HBc, negative HBsAg 1
- Chronic infection: Positive HBsAg for >6 months, positive anti-HBc, negative anti-HBs 1
- Acute infection: Positive HBsAg, positive IgM anti-HBc 1
- Isolated anti-HBc: Negative HBsAg, negative anti-HBs, positive anti-HBc - may indicate occult hepatitis B, resolved infection with waning anti-HBs, or false positive 1
Clinical Considerations
- Testing for hepatitis titers is particularly important for patients with chronic liver disease who may need vaccination 3
- Sequential testing is recommended for patients with indeterminate results (isolated anti-HBc) with repeat testing in 3-6 months 1
- Patients with chronic HBV should be tested for HAV immunity and vaccinated if negative for anti-HAV 1, 4
- For patients with occupational exposure or healthcare workers, both anti-HBs and anti-HBc should be tested to distinguish between vaccine-induced and infection-induced immunity 1
Pitfalls and Caveats
- False negative anti-HBs can occur in immunocompromised patients despite immunity 1
- The "window period" during acute HBV infection may show negative HBsAg but positive IgM anti-HBc 1
- Low-level anti-HBc IgM can be present in chronic HBV infection, potentially causing confusion with acute infection 2, 5
- Isolated anti-HBc requires careful interpretation and may necessitate HBV DNA testing to rule out occult HBV infection 1
- Anti-HBs levels may decline over time after vaccination but most individuals retain immune memory 1