Hepatitis B surface antigen (HBsAg) positive

Hepatitis B virus surface antigen (HBsAg) is the outer membrane protein of hepatitis B virus (HBV), which can appear early after infection with HBV. Hepatitis B surface antigen (HBsAg) is the coat protein of hepatitis B virus, which is not infectious in itself, but its appearance is often accompanied by the presence of hepatitis B virus, so it is a sign of infection with hepatitis B virus. It can be found in patients' blood, saliva, breast milk, sweat, tears, nasopharyngeal secretions, semen and vaginal secretions. Two to six months after infection with hepatitis B virus, positive results can be detected in the serum 2 to 8 weeks before the alanine aminotransferase is elevated. Most patients with acute hepatitis B can turn negative early in the course of the disease, and chronic hepatitis B patients can continue to be positive for this indicator.