What is the recommended workup for Hepatitis A (Hep A)?

Hepatitis A Workup

Diagnostic Testing

The diagnosis of acute hepatitis A requires serologic testing for IgM anti-HAV antibodies, which is the only test needed to confirm acute infection. 1, 2

Primary Diagnostic Test

• IgM anti-HAV is the definitive test for acute hepatitis A infection and becomes detectable 5-10 days before symptom onset in most patients 1
• This single test is sufficient to confirm the diagnosis—no other hepatitis A-specific testing is required for acute infection 2
• IgM anti-HAV remains positive for up to 6 months after infection in most patients 1

Important Diagnostic Caveat

• Rare false-negative results can occur early in infection: If clinical suspicion remains high despite negative IgM anti-HAV, repeat testing in 3-7 days is warranted 3
• One documented case showed undetectable IgM anti-HAV at initial presentation despite several days of symptoms, with subsequent testing revealing positive results 3

Immunity Testing (When Indicated)

• Total anti-HAV (IgG + IgM) or IgG anti-HAV indicates past infection or vaccination and lifelong immunity 1, 2
• Pre-vaccination screening for anti-HAV antibodies should be considered in populations where prevalence exceeds 33%, including adults >50 years, foreign-born individuals, and persons with chronic liver disease 1, 4

Additional Workup for Confirmed Cases

Essential Laboratory Tests

• Complete blood count to assess for leukocytosis or other hematologic abnormalities 2
• Comprehensive liver panel including:
  • AST/ALT (typically markedly elevated) 1
  • Alkaline phosphatase and GGT 1
  • Total and direct bilirubin 1
  • Albumin 1
  • Prothrombin time/INR (critical for assessing liver synthetic function) 1

Screening for Coinfections

All patients with confirmed hepatitis A should be tested for other viral hepatitis infections, as coinfection significantly increases morbidity and mortality. 1

• Hepatitis B serologies: HBsAg, anti-HBs, and anti-HBc total 1
• Hepatitis C antibody (with reflex HCV RNA if positive) 1
• HIV testing in high-risk populations 1
• Anti-HDV (hepatitis D) in patients with history of injection drug use 1

The rationale is critical: patients with chronic liver disease (especially hepatitis B or C) have substantially higher rates of fulminant hepatic failure and mortality when infected with HAV 1, 4

Risk Stratification and Monitoring

Indicators for Hospitalization

• Severe dehydration from intractable vomiting requiring IV fluids 2
• Signs of acute liver failure: encephalopathy, coagulopathy (INR >1.5), or rapidly rising bilirubin 2
• Underlying chronic liver disease of any etiology 2
• Age >50 years (case-fatality rate reaches 1.8% in this group) 1

Outpatient Management Criteria

• Adequate oral hydration tolerance 2
• Normal mental status 2
• INR <1.5 2
• No underlying chronic liver disease 2
• Reliable follow-up available 2

Contact Tracing and Prevention

Post-Exposure Prophylaxis Evaluation

Identify and treat close contacts within 2 weeks of exposure for maximum efficacy. 1, 2

• Household contacts should receive immune globulin (0.02 mL/kg) if unvaccinated 1
• Sexual contacts require IG administration 1
• Persons sharing illicit drugs with the index case need IG plus hepatitis A vaccine 1
• Child care center staff and attendees if outbreak criteria are met 1

Vaccination Assessment

• Determine hepatitis A immunity status in household contacts 1
• Vaccinate susceptible contacts, particularly those with chronic liver disease, men who have sex with men, and injection drug users 1