What to check next if Hepatitis A (Hep A) antibody is positive?

Next Steps After Positive Hepatitis A Antibody Test

If a patient has a positive Hepatitis A antibody test, the next step should be to determine which specific antibody is positive (IgM vs IgG) and conduct appropriate follow-up testing to establish the clinical significance of the finding. 1

Interpreting Hepatitis A Antibody Results

If IgM Anti-HAV Positive:

• IgM antibody to HAV is diagnostic of acute HAV infection 1
• Confirm the result is a true positive by evaluating:
  • Clinical symptoms (jaundice, nausea, vomiting, abdominal pain) 1, 2
  • Liver function tests (elevated ALT/AST, bilirubin) 1, 2
  • Risk factors for HAV exposure 1
• Be aware that false-positive IgM results can occur, especially in patients with other liver diseases or in low-prevalence settings 3, 4
• Low-level positive IgM results without clinical symptoms often do not represent acute infection 4

If IgG Anti-HAV Positive (or Total Anti-HAV Positive with Negative IgM):

• Indicates immunity to HAV due to:
  • Previous infection (resolved) 1
  • Previous vaccination 1
• No further hepatitis A-specific testing is needed 1

Additional Testing to Consider

For Suspected Acute Hepatitis A:

• Complete blood count 1
• Comprehensive liver panel: AST, ALT, alkaline phosphatase, gamma-glutamyl transpeptidase, bilirubin, albumin, prothrombin time 1
• Consider testing for other viral hepatitis infections to rule out co-infections:
  • HBsAg, anti-HBc, anti-HBs 1
  • Anti-HCV and HCV RNA if anti-HCV positive 1, 5
  • Anti-HDV in patients with history of drug abuse 1
  • Anti-HIV in high-risk groups 1

For Patients with Chronic Liver Disease:

• Consider autoimmune markers if autoimmune hepatitis is suspected, as HAV can trigger autoimmune hepatitis 1, 6:
  • Antinuclear antibodies (ANA)
  • Smooth muscle antibodies (SMA)
  • Anti-liver/kidney microsome type 1 (LKM-1)
  • Anti-soluble liver antigen (SLA) 1

Management Based on Results

For Acute Hepatitis A:

• Supportive care is usually sufficient 1
• No restrictions in diet or activity typically needed 1
• Hospitalization may be necessary for:
  • Dehydration due to nausea and vomiting 1
  • Signs or symptoms of acute liver failure 1
• Medications that might cause liver damage should be used with caution 1

For Patients with Positive IgG Anti-HAV Only:

• No specific treatment needed - patient is immune 1
• Consider vaccination for other viral hepatitis (HBV) if not already immune 1

For Patients with Negative HAV Immunity:

• Consider HAV vaccination, especially for:
  • Men who have sex with men 1
  • Injection drug users 1
  • Persons with chronic liver disease 1
  • Travelers to countries with high HAV endemicity 1
  • Patients with HBV and/or HCV infection 1

Common Pitfalls to Avoid

• Misinterpreting isolated positive IgM anti-HAV without clinical correlation 3, 4
• Failing to consider other causes of liver disease when HAV antibodies are positive 3
• Not testing for other viral hepatitis markers in patients with liver disease 1
• Overlooking the possibility of autoimmune hepatitis triggered by acute HAV infection 6