HBsAg

HBsAg, the hepatitis B surface antigen, is a blood test that screens for active infection with the hepatitis B virus. It detects a protein found on the surface of the virus itself.

A positive HBsAg result suggests a current hepatitis B infection and usually leads to further tests to assess the situation more fully. Detecting it early allows for appropriate monitoring and care, and results are always handled with confidentiality.