What does a reactive hepatitis A, antibody (AB) total, result mean?

Meaning of Hepatitis A, AB Total, Reactive

A reactive hepatitis A total antibody (AB total) result indicates immunity to hepatitis A virus, either from past infection or successful vaccination, conferring lifelong protection against future infections. 1

Interpretation of Hepatitis A Antibody Testing

Hepatitis A antibody testing involves two main types of tests:

1. Total HAV antibody test (AB total):

   • Measures both IgM and IgG antibodies
   • Used primarily for screening for immunity
   • A reactive (positive) result indicates either:
     • Past infection with recovery
     • Successful vaccination
     • Recent or current infection

2. IgM-specific HAV antibody test:

   • Used specifically to diagnose acute infection
   • Appears 5-10 days before symptom onset
   • Indicates acute or recent HAV infection (within past 6 months)

Clinical Significance of Your Result

When the total HAV antibody test is reactive but IgM testing is not performed or is negative, this indicates:

• You have immunity against hepatitis A virus
• This immunity is lifelong and protective
• No hepatitis A vaccination is required
• No post-exposure prophylaxis would be needed if exposed to HAV in the future

Potential Scenarios for Reactive Total HAV Antibody

1. Past infection with complete recovery

   • Most common scenario in adults with reactive total antibody
   • Indicates you've been infected with HAV in the past and have recovered
   • Provides lifelong immunity

2. Successful vaccination

   • If you've received hepatitis A vaccine in the past
   • Vaccination provides long-term protection similar to natural infection

3. Very early acute infection (rare scenario)

   • In some cases, very early in acute infection, total antibody may be reactive while IgM is still non-reactive
   • This is uncommon but possible due to differences in assay sensitivity 2
   • If you have symptoms of hepatitis (jaundice, fever, nausea, abdominal pain), additional testing may be warranted

Clinical Implications

• No need for vaccination: Individuals with positive total HAV antibody do not require hepatitis A vaccination as they already have immunity 1

• Protection against future exposure: You are protected if exposed to the hepatitis A virus in the future 1

• Differentiation from acute infection: To distinguish between immunity and acute infection, an IgM-specific test would be needed if there are clinical symptoms suggesting acute hepatitis

Important Considerations

• If you have symptoms of acute hepatitis (jaundice, fever, abdominal pain, elevated liver enzymes), an IgM-specific test should be performed to rule out acute infection, as some early cases of hepatitis A can show reactive total antibody before IgM becomes detectable 2, 3

• False positive results for HAV IgM can occur in patients with other liver diseases, so clinical correlation is important when interpreting hepatitis A serology 4

• The presence of total HAV antibodies without IgM is a reliable indicator of immunity rather than acute infection in asymptomatic individuals 1