If a patient has HepB surface antigen, what does it indicate?

The presence of Hepatitis B surface antigen (HBsAg) in a patient's blood is a crucial marker for evaluating Hepatitis B infection. Specifically, HBsAg indicates that the person is currently infected with the Hepatitis B virus (HBV), either in an acute or chronic phase of the infection.

When HBsAg is detected, it means that viral proteins are present in the bloodstream, suggesting active viral replication and contagion risk. This is typically one of the first serological markers to appear soon after infection and can persist for several weeks to months, depending on the individual's immune response.

In contrast, the presence of Hepatitis B surface antibody (anti-HBs) would indicate recovery and immunity from Hepatitis B, usually seen after vaccination or following clearance of the infection. Therefore, the detection of HBsAg uniquely points to an active infection, making it a significant diagnostic indicator in managing Hepatitis B.