HBsAg is the surface antigen detected in the blood from a person infected with Hepatitis B virus (HBV).It is also known as Australia antigen, since it was first isolated in the serum of an Australian.
If the blood test is positive for HBsAg, it indicates that person is infected with hepatitis B. Majority of HBsAg patients may be healthy without any symptoms, but some may have biochemical or histological evidence of chronic liver diseases.
Nowadays, blood donors are screened for HBsAg before transfusion, and this has reduced the post transfusion infection almost completely.
In blood examination, if it says HBsAg positive means, you have active hepatitis B infection and can pass the virus to others through their blood or infected body fluids.
In blood examinations if the level of HbsAg is less than 1s/c (signal per cutoff) it is considered as negative. And the value above 5 s/c is positive. Since there is no clear-cut standardization between laboratories the values are noted as positive or negative.
