Hepatitis B Surface Antigen
Hepatitis B surface antigen (HBsAg) is a protein found on the surface of the hepatitis B virus. HBsAg screening is a blood test that shows whether the hepatitis B virus is present.
Why it matters: A positive or reactive confirmatory result means the hepatitis B virus is present, in someone who has not recently been vaccinated. A negative result means there is no active hepatitis B infection. A hepatitis B vaccine given in the past few weeks makes a positive result likely, and the test is then repeated a few weeks later.
Source · Cleveland Clinic — what it is, why it matters, related conditions
What is Hepatitis B Surface Antigen?
Hepatitis B surface antigen (HBsAg) is a protein found on the surface of the hepatitis B virus. HBsAg screening is a blood test that shows whether the hepatitis B virus is present.
What might a high or low Hepatitis B Surface Antigen mean?
A positive or reactive confirmatory result means the hepatitis B virus is present, in someone who has not recently been vaccinated. A negative result means there is no active hepatitis B infection. A hepatitis B vaccine given in the past few weeks makes a positive result likely, and the test is then repeated a few weeks later.
Track your Hepatitis B Surface Antigen over time
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