Hepatitis B tests
Also known as: hepatitis B serology, hepatitis B blood test, HBV testing, hepatitis B surface antigen test
A set of blood tests that shows whether someone has hepatitis B now, had it in the past, is immune from vaccination, or carries the virus long term. Each marker answers a different question: the surface antigen shows current infection, the antibodies show immunity or past exposure, and the viral DNA measures how actively the virus is multiplying.
- Abbreviations
- HBsAg, anti-HBs, anti-HBc
- Kind
- Laboratory test
- Categories
- Infectious disease & microbiology, Liver & hepatobiliary
- Specimen
- Serum
- Method
- Immunoassay, PCR (including RT-PCR and qPCR)
- Terminology
- LOINC 5196-1
- Type
- Blood test (serology and PCR)
- Sample
- Blood from a vein
- Used for
- Diagnosing and monitoring hepatitis B, checking immunity, screening in pregnancy and before immunosuppression
- Measures
- Hepatitis B antigens, antibodies and viral DNA
- Result
- Positive or negative markers read as a pattern, plus a viral load
Why is it used?
- Abnormal liver tests or symptoms of hepatitis
- Screening in pregnancy, before immunosuppressive treatment, and in people at higher risk
- After a possible exposure, such as a needlestick injury
- Checking immunity after vaccination
- Monitoring chronic hepatitis B and its treatment
What does it measure?
| Measure | What it tells you |
|---|---|
| Hepatitis B surface antigen (HBsAg) | Part of the virus's outer coat; present in acute and chronic infection. Persisting beyond six months defines chronic hepatitis B. |
| Hepatitis B surface antibody (anti-HBs) | The protective antibody; present after vaccination or recovered infection. |
| Hepatitis B core antibody (anti-HBc) | Marks exposure to the virus at some time; absent after vaccination alone. The IgM form points to recent infection. |
| e antigen and e antibody (HBeAg, anti-HBe) | Indicate how actively the virus is replicating in chronic infection. |
| HBV DNA (viral load) | The amount of virus in the blood, measured by PCR; guides the decision to treat and shows whether treatment is working. |
A high or low value can be associated with several different situations; the result is interpreted with other results, symptoms, history and clinical findings.
How is it performed?
A venous blood sample; the laboratory runs the markers as a panel and adds viral DNA when the surface antigen is positive.
Specimen. Venous blood (serum)
Do I need to prepare?
None.
What do the results generally mean?
| Finding | What it may indicate |
|---|---|
| HBsAg positive | Current infection, acute or chronic; further markers and liver assessment follow, and specialist care is arranged |
| anti-HBs positive, anti-HBc negative | Immunity from vaccination |
| anti-HBs and anti-HBc positive, HBsAg negative | Past infection that has resolved, with immunity |
| HBsAg positive for more than six months | Chronic hepatitis B; the viral load, e-antigen status and liver tests decide on monitoring and antiviral treatment |
| All markers negative | Never infected and not immune; vaccination is considered |
What can affect the result?
- Timing after exposure: markers appear in sequence over weeks
- Recent vaccination, which produces anti-HBs only
- Immunosuppression, which can reactivate a resolved infection
- Very early or 'window period' infection, when only anti-HBc IgM may be positive
Medicines. Antiviral treatment for hepatitis B lowers the viral load; the test monitors that treatment. Immunosuppressive medicines can reactivate the virus, so screening is done before they are started.
What can the test not tell you?
- How much liver damage has occurred, which needs liver tests, elastography or biopsy
- Whether hepatitis C, D or other liver diseases are also present without their own tests
- Exactly when the infection was acquired
The markers must be read as a pattern; a single result can mislead in the window period, after vaccination or in people with weak immunity. Chronic infection needs long-term specialist monitoring even when the person feels well.
Other tests commonly used with it
Catalogued concepts this page covers
Concepts of the master test taxonomy that resolve to this page; each links to its category.