In evaluating Hepatitis B, which test is used to determine active infection?

In evaluating Hepatitis B, which test is used to determine active infection?

• A. anti-HBc
• B. anti-HBs
• C. HBsAg
• D. HBV DNA

Answer: (C)

Detecting active Hepatitis B hinges on the presence of the viral surface antigen in the blood. If this surface antigen is present, there is an active infection and the person can be infectious, whether it's acute or chronic. Absence of the surface antigen means no active infection, while antibodies tell us different things: anti-HBs indicates immunity (from vaccination or recovery), and anti-HBc shows prior exposure. HBV DNA directly measures the amount of viral genetic material and is used to gauge replication level and monitor treatment, but the standard marker to declare an active infection is the presence of HBsAg.

Detecting active Hepatitis B hinges on the presence of the viral surface antigen in the blood. If this surface antigen is present, there is an active infection and the person can be infectious, whether it's acute or chronic. Absence of the surface antigen means no active infection, while antibodies tell us different things: anti-HBs indicates immunity (from vaccination or recovery), and anti-HBc shows prior exposure. HBV DNA directly measures the amount of viral genetic material and is used to gauge replication level and monitor treatment, but the standard marker to declare an active infection is the presence of HBsAg.