A doctor or health clinic provides hepatitis B blood testing, according to the Hepatitis B Foundation. Only one blood sample is necessary, but the test involves three results: hepatitis B surface antigen, hepatitis B surface antibody and hepatitis B core antibody.
It takes four to six weeks after initial infection for the hepatitis B virus to show up in the blood, notes the Hepatitis B Foundation. Sometimes, a doctor requires an additional blood test six months after the initial visit to confirm a patient's status.
People at greater risk for hepatitis B include prison inmates, people on kidney dialysis, intravenous drug users, pregnant women and certain immigrants, according to the Mayo Clinic.