HBsAg enzyme immunoassay is the first serological marker to appear in the serum at 1 to 10 weeks after infection with HBV and 2 to 8 weeks before the onset of clinical symptoms of hepatitis B.
After the acute infection of hepatitis B, HBsAg typically disappears 1 to 3 months after symptom onset.
The persistence of HBsAg for more than six months is consistent with the diagnosis of chronic HBV and is the primary indicator of risk for developing chronic liver disease and hepatocellular carcinoma later in life.
HBsAg Therefore can help with the diagnosis of both acute and chronic hepatitis B.
A negative HBsAg Test rules out acute hepatitis B infection except for the time between 100 and 160 days after the symptom onset when HBsAg disappears and before anti-HBs appear.
During this time, the total and IgM hepatitis B core antibodies (anti-HBc) are the only serological markers present.
Pooled data suggests a 88.9% sensitivity and a 98.4% specificity for HBsAg testing for chronic hepatitis B.
HBsAg is indicated in the absence of signs and symptoms for asymptomatic patients at high risk for exposure to HBV, such as patients receiving dialysis or individuals who inject illicit drugs, or an asymptomatic persons at risk for severe adverse outcomes from undiagnosed HBV infection, such as individuals requiring immuno suppressive therapy or pregnant women.
Hepatitis Be antigen (HBeAg) is the soluble part of the core antigen of HBV.
The presence of HBeAg typically indicates active HBV replication, greater infectivity and higher serum levels of HBV DNA.
Anti–HBe antibodies indicate lower infectivity and lower serum levels of HBV DNA.
Resolution of HBV infection is characterized by a negative HBsAg test results with positive anti-HBs and IgG anti-HBc test results.
In acute HBV infection HBsAg and total and IgM hepatitis B core (anti-HBc) antibody test results are positive but hepatitis B surface antibody (anti-HBs) results are negative.
Chronic HBV infection is characterized by a positive HBsAg and anti-HBc test results but negative IgM anti-HBc and anti-HBs results.