HBsAg

HBsAg (Hepatitis B surface antigen) is a protein found on the surface of the hepatitis B virus. Its presence in the blood indicates that a person is infected with hepatitis B, either currently or at some point in the past. If HBsAg is detected during testing, it means the virus is active and can potentially be transmitted to others through blood or bodily fluids. The test helps diagnose hepatitis B infection, monitor treatment, and determine if someone has become immune after recovering or vaccination. Persistent HBsAg usually signifies chronic hepatitis B infection.