What it means
The surface antigen appears in the blood when a person is infected with hepatitis B virus. A positive test means current infection, either new (acute) or long-term (chronic, when it stays positive for more than 6 months), and that the person can pass the virus on through blood and body fluids. It is read with other hepatitis B tests; the antibody to the surface antigen (anti-HBs) shows immunity from vaccination or past infection.
For the nurse
It is a routine prenatal test. A newborn whose birthing parent is positive receives hepatitis B vaccine and hepatitis B immune globulin (HBIG) within 12 hours of birth.
At a glance
| Normal range | Negative |
|---|---|
| Also written | HBsAg |
Related terms
vaccine
A product that trains the immune system to protect the body against a specific disease.
hepatitis B
A liver infection caused by the hepatitis B virus.
lamivudine
An oral antiviral drug used with other drugs to treat HIV, and alone to treat chronic hepatitis B.