This is the primary test to take to determine exposure to Hepatitis B. The Hepatitis B Surface Antigen lab test evaluates blood donors (HBsAg positive individuals are rejected). Hepatitis B surface antigen is the earliest indicator of the presence of acute infection. Also indicative of chronic infection. Test is useful in the differential diagnosis of hepatitis.

Hepatitis B virus (HBV) is a DNA virus with a protein coat, the surface antigen (HBsAg) and a nucleic acid core, the core antigen (HBcAg). There are eight different serotypes. Early in infection, HBsAg, HBV DNA, and DNA polymerase can all be detected in serum.

HBsAg can be detected one to seven weeks before liver enzyme elevation or the appearance of clinical symptoms. Three weeks after the onset of acute hepatitis, about 50% of patients will still be positive for HBsAg, while at 17 weeks only 10% are positive. The best available markers for infectivity are HBsAg and HBeAg. The presence of anti-HBs is frequently associated with noninfectivity. The chronic carrier state is indicated by the persistence of HBsAg and/or HBeAg over long periods (six months to years) without seroconversion to the corresponding antibodies. Such a condition has the potential to lead to serious liver damage, but may be an isolated asymptomatic serologic phenomenon.

Persistence of HBsAg, without anti-HBs, with combinations of positivity of anti-HBc, HBeAg, or anti-HBe indicates infectivity and need for investigation for chronic persistent or chronic aggressive hepatitis.

Test Includes:

Confirmation of a positive result by a neutralization assay at no additional charge

Synonyms:

• HAA
• HBsAg
• Hepatitis-associated Antigen