hepatitis B surface antigen ( HBsAg )

Last reviewed 01/2018


  • this is the earliest indicator of hepatitis B infection
  • generally appears in 27-41 days - may occur as early as 14 days
  • appears 7-26 days before biochemical abnormalities occur
  • this indicator persists during the acute illness
  • generally disappears 1-13 weeks after the onset of biochemical abnormalities
  • this is the most reliable serologic marker of hepatitis B virus infection
  • this indicator may also be found in chronic infection
    • HBsAg is a viral protein detectable in the blood in acute and chronic hepatitis B infection (1)
  • hepatitis B vaccination does not result in a positive HBsAg

HBsAg seroconversion

  • the development of antibodies against HBsAg is known as HBsAg seroconversion. It signifies clearance of HBsAg and resolution of the chronic infection.