Clinical and Interpretive

This assay is used in the diagnosis of acute, recent, or chronic hepatitis B infection and in the determination of chronic hepatitis B infection status.

Hepatitis B virus (HBV) is endemic throughout the world. The infection is spread primarily through percutaneous contact with infected blood products (eg, blood transfusion, sharing of needles by intravenous drug addicts). The virus is also found in various human body fluids, and it is known to be spread through oral and genital contacts. HBV can be transmitted from mother to child during delivery through contact with blood and vaginal secretions, but it is not commonly transmitted transplacentally.

Hepatitis B surface antigen (HBsAg) is the first serologic marker appearing in the serum at 6 to 16 weeks following exposure to HBV. In acute infection, HBsAg usually disappears in 1 to 2 months after the onset of symptoms. Persistence of HBsAg for >6 months in duration indicates development of either a chronic carrier state or chronic HBV infection.

Specimens with reactive screen results but negative (ie, not confirmed) HBsAg confirmatory test results are likely to contain cross-reactive antibodies from other infectious or immunologic disorders. Repeat testing is recommended at a later date if clinically indicated.Confirmed presence of HBsAg is frequently associated with HBV replication and infectivity, especially when accompanied by presence of hepatitis B envelope (HBe) antigen and/or detectable HBV DNA.

Not useful during “window period” of acute hepatitis B virus (HBV) infection (ie, after disappearance of hepatitis B surface antigen [(HBsAg] and prior to appearance of hepatitis B surface antibody [anti-HBs]). Testing for acute HBV infection should also include hepatitis B core IgM antibody (anti-HBc IgM).Not suitable as stand-alone prenatal screening test of HBsAg status in pregnant women.

Individuals, especially neonates and children, who recently received hepatitis B vaccination may have transient positive HBsAg test results because of the large dose of HBsAg used in the vaccine relative to the individual’s body mass.