Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1371 page)

   Limitations

   Vaccination for HBV can produce transiently detectable levels of HBsAg in patients (≤14 days). Most commonly occurs in hemodialysis patients, neonates, and children.

   Some rare mutations result in false-negative test results. In these suspected cases, the presence of virus can be deduced by testing for HBcAb, surface antigen antibodies, and HBV DNA.

   Specimens with initially reactive test result but negative (not confirmed) by HBsAg confirmation test are likely to contain cross-reactive antibodies from other infectious or immunologic disorders. Repeat testing is recommended at a later date when clinically indicated.

HEPATITIS BE ANTIGEN AND ANTIBODY (HBeAg AND HBeAb)

   Definition

   Presence of HBeAg in the serum indicates active replication of virus and is usually associated with HBV DNA. HBeAg to HBeAb seroconversion occurs early in patients with acute infection, prior to HBsAg-to-HBsAb seroconversion. However, HBeAg seroconversion may be delayed for years to decades in chronic infection. HBeAg-to-HBeAb seroconversion usually associated with disappearance of HBV DNA in serum. Presence of HBeAb in the serum usually indicates that the virus is no longer replicating. Limited use clinically.

   
Normal range:
Negative.

   Use

   Diagnosis and monitoring of HBV infectivity. Recognition of resolution of hepatitis B infection with seroconversion of HBeAg to HBeAb.

   Interpretation

   Presence indicates highly infective stage of hepatitis B.

   Limitations

   Persistence of HBeAg is associated with chronic liver disease.