Key facts
- Hepatitis B affects the liver and may be present without noticeable symptoms.
- A person can have hepatitis B even when they feel well.
- HBsAg and hepatitis B surface antibody tests provide different types of information.
- A reactive or abnormal hepatitis B test result may need further assessment.
- Liver-function tests can provide additional information about liver health but do not replace hepatitis B-specific testing.
Signs and symptoms
Hepatitis B may cause no noticeable symptoms.
When symptoms do occur, they can include fatigue, abdominal discomfort or joint discomfort. Symptoms alone cannot confirm hepatitis B, so blood testing is needed when infection is being assessed.
Risk factors
Previous exposure to hepatitis B
Close or household exposure where hepatitis B may be present
Sexual or blood exposure that may involve hepatitis B
Pregnancy or birth-related hepatitis B considerations
A previous hepatitis B test result that needs follow-up
Common causes
Hepatitis B is caused by infection with the hepatitis B virus. Transmission can occur through exposure to infected blood or body fluids, including sexual, blood and birth-related exposure. The circumstances of possible exposure help guide which tests and follow-up may be appropriate.
How it is checked
Hepatitis B is assessed using specific blood tests. Hepatitis B surface antigen and surface antibody provide different information, while liver-function tests may help assess liver health when appropriate. Results need to be interpreted together rather than treating one marker as a complete hepatitis B assessment.
Assessment and investigations
Hepatitis B Surface Antigen
Hepatitis B surface antigen, often called HBsAg, is used when assessing whether hepatitis B infection may be present. A reactive result needs appropriate clinical interpretation and follow-up.
Hepatitis B Surface Antibody
Hepatitis B surface antibody provides different information from HBsAg and may be used when assessing hepatitis B immunity or previous immune response. It should not be interpreted as the same test as hepatitis B surface antigen.
Liver Function Test
Liver-function blood tests can provide information about liver health when hepatitis B is being assessed, but they do not determine hepatitis B infection status by themselves.
When to see a doctor
Consider speaking with a doctor if you think you may have been exposed to hepatitis B, have received a reactive or unclear hepatitis B test result, have persistent unexplained symptoms, or need help understanding your hepatitis B infection or immunity status.
Frequently asked questions
Can hepatitis B have no symptoms?
Yes. Hepatitis B can be present without noticeable symptoms, which is why blood testing can be important when infection or previous exposure needs to be assessed.
What is HBsAg?
HBsAg stands for hepatitis B surface antigen. It is one of the blood markers used when assessing hepatitis B infection, and a reactive result needs appropriate clinical interpretation and follow-up.
What is the difference between HBsAg and hepatitis B antibody?
HBsAg and hepatitis B surface antibody provide different information and are not interchangeable. One relates to infection assessment, while the antibody test can provide information about immunity or previous immune response.
What should I do if my hepatitis B test is reactive?
A reactive result should be discussed with a healthcare professional because one result may not provide the complete picture and further assessment or additional testing may be needed.