What tests should be ordered to determine hepatitis immunity?

Hepatitis Tests to Determine Immunity

To determine hepatitis immunity status, order HBsAg, anti-HBs, and anti-HBc as the standard panel for hepatitis B, and anti-HAV for hepatitis A immunity. 1, 2

Hepatitis B Immunity Testing

Standard Testing Panel

• HBsAg (Hepatitis B Surface Antigen): Indicates current acute or chronic infection
• Anti-HBs (Antibody to Hepatitis B Surface Antigen): Indicates immunity (from vaccination or resolved infection)
• Anti-HBc (Antibody to Hepatitis B Core Antigen): Indicates previous or ongoing infection

Interpretation of Results

1. Immunity from vaccination:

   • Negative HBsAg
   • Positive anti-HBs (≥10 mIU/mL)
   • Negative anti-HBc 2

2. Immunity from resolved infection:

   • Negative HBsAg
   • Positive anti-HBs
   • Positive anti-HBc 1, 2

3. Current infection:

   • Positive HBsAg
   • Negative anti-HBs
   • Positive anti-HBc 1

4. No immunity (susceptible):

   • Negative HBsAg
   • Negative anti-HBs
   • Negative anti-HBc 1

5. Isolated anti-HBc positive:

   • Negative HBsAg
   • Negative anti-HBs
   • Positive anti-HBc
   • Consider HBV DNA testing to rule out occult hepatitis B 1

Hepatitis A Immunity Testing

• Anti-HAV (Total): Test for antibodies to hepatitis A virus to determine immunity status 1, 2
• Positive result indicates immunity from prior infection or vaccination

Additional Considerations

Special Populations

• Hemodialysis patients: Annual testing of anti-HBs is recommended; booster vaccination needed if anti-HBs <10 mIU/mL 1
• Immunocompromised patients: May require more frequent monitoring of antibody levels 1
• Chronic liver disease patients: Should be tested for both HAV and HBV immunity due to increased risk of severe disease with superinfection 3, 4

Common Pitfalls to Avoid

1. Incomplete testing: Testing only for HBsAg and anti-HBs without anti-HBc can miss patients in the "window period" of acute infection or those with occult hepatitis B 1

2. Misinterpreting recent passive immunity: Recent administration of hepatitis B immune globulin can cause transient positive anti-HBs without true immunity 5

3. Assuming immunity is permanent: Anti-HBs levels may decline over time, particularly in immunocompromised patients 1

4. Failing to test for HAV immunity: Patients with chronic HBV infection should be tested for HAV immunity, as HAV superinfection increases mortality risk 5.6-29 fold 1

Post-Testing Actions

• For individuals without immunity to hepatitis B, vaccination is recommended 1
• For individuals without immunity to hepatitis A, particularly those with chronic liver disease, hepatitis A vaccination is recommended 1, 3
• Postvaccination testing for anti-HBs is recommended for certain high-risk groups (immunocompromised patients, hemodialysis patients) 1

By following this comprehensive testing approach, clinicians can accurately determine hepatitis immunity status and take appropriate preventive measures to protect patients from these potentially serious viral infections.