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Hepatitis B: HB Surface Antigen (HBs Ag)

HBsAg refers to the hepatitis B surface antigen, a protein that is present on the surface of the hepatitis B virus (HBV). HBsAg testing is used to diagnose and monitor HBV infection. When a person is infected with HBV, their immune system produces HBsAg as the virus replicates. HBsAg is the earliest and most reliable marker of acute HBV infection and can be detected in the blood within 1-10 weeks after exposure to the virus. It is also present in the blood of people with chronic HBV infection and can be used to monitor the effectiveness of treatment. HBsAg testing is typically done in conjunction with other HBV tests, such as hepatitis B core antibody (HBcAb) and hepatitis B surface antibody (HBsAb) tests. The combination of these tests can help determine the stage of HBV infection, as well as the risk of developing chronic liver disease. In addition to diagnosing and monitoring HBV infection, HBsAg testing is also used to screen blood donors and healthcare workers for HBV infection. It is recommended as a routine part of prenatal care to identify pregnant women who are infected with HBV and may transmit the virus to their newborns. Overall, HBsAg testing is an important tool in the diagnosis and management of HBV infection. Early detection and treatment can help prevent the development of serious liver disease, such as cirrhosis and liver cancer.

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