What does HBsAg indicate in a patient?

HBsAg, or Hepatitis B surface antigen, serves as a crucial marker for identifying an active Hepatitis B infection. When HBsAg is present in a patient's serum, it confirms that the patient is currently infected with the Hepatitis B virus. Additionally, the presence of this antigen signifies that the individual is potentially infectious, meaning that they can transmit the virus to others.

In clinical practice, testing for HBsAg is a standard approach for diagnosing Hepatitis B. A positive result indicates an ongoing infection, allowing healthcare providers to implement necessary treatment and preventive measures.

This is in contrast to other indicators like antibodies (such as anti-HBs), which signify recovery or immunity, or HBeAg, which reflects viral replication. Thus, the significance of HBsAg as an active infection marker makes it an essential component in managing and understanding Hepatitis B disease dynamics.