Related Articles
Learn about how the hepatitis B surface antibody test works, and how its results indicate immunity to the virus
Hepatitis B surface antibodies (anti-HBs or HBsAb) are measured in blood samples in milli-International Units/milliliter mIU/mL). The ranges for hepatitis B surface antibodies are:
- Anti-HBs greater than 10-12 mIU/mL: Protected against hepatitis B virus (HBV) infection, either from vaccination or successful recovery from a previous HBV infection.
- Anti-HBs less than 5 mIU/mL: Negative for HBV infection, but susceptible and hence requires vaccination.
- Anti-HBs from 5-12 mIU/mL: Inconclusive results and the test should be repeated.
However, there is no standardization of these values so it is advisable to check the manufacturers values; it is the reason values are mainly reported as positive or negative.
What is a hepatitis B surface antibody test?
Hepatitis B surface antibody test is part of a panel of blood tests to diagnose HBV infection. Hepatitis B surface antibody test determines the presence and quantity of anti-HBs in the blood serum, which can indicate protection from HBV infection.
Hepatitis B disease affects the liver and commonly spreads through body fluids such as blood, semen, and vaginal secretions.
What is the difference between hepatitis B surface antibody and antigen?
An antigen is a substance that induces antibody production. Hepatitis B surface antigen (HBsAg) is a protein on the surface of hepatitis B virus.
Hepatitis B surface antibodies are produced by the body’s immune system in response to HBsAg. The presence of adequate hepatitis B surface antibodies in the blood indicates protection against hepatitis B virus infection.
Does hepatitis B show up in routine blood tests?
Routine blood tests do not detect hepatitis B virus infection. Hepatitis B tests are specifically done if blood tests show abnormal liver function results, or if a person experiences symptoms or falls into the high-risk category for HBV infection.
A panel of HBV-specific blood tests are required to detect HBV infection.
What is the purpose of a hepatitis B test?
Hepatitis B test is performed to detect, classify, and treat hepatitis B virus infection.
Hepatitis B blood tests involve the measurement of several HBV-specific antigens and antibodies. In addition, HBV blood tests also include liver enzymes and liver function tests to assess and monitor the condition of the liver and provide appropriate treatment.
The HBV specific tests include the following:
- HBsAg: HBsAg is an antigen found on the surface of hepatitis B virus. HBsAg may be detected in the blood any time after 1 week post-exposure to HB virus, but usually appears after 4 weeks.
- Anti-HBs: Anti-HBs are antibodies produced by the body’s immune system to fight HBsAg. Anti-HBs from a prior infection or vaccination provides immunity against further infection.
- Hepatitis B core antigen (HBcAg): HBcAg is an antigen found in the core layer which covers the hepatitis B viral DNA.
- Hepatitis B core antibody (anti-HBc): Anti-HBc is the antibody that fights HBcAg. Anti-HBc is the first detectable antibody after HBV infection. There are two kinds of Anti-HBc:
- Immunoglobulin M hepatitis B core antibody (IgM anti-HBc): IgM anti-HBc indicates acute or reactivated recent infection within the previous 6 months.
- Immunoglobulin G hepatitis B core antibody (IgG anti-HBc): IgG anti-HBc may indicate previous or chronic infection. Once present, IgG anti-HBc persists for a lifetime.
- Hepatitis B e-antigen (HBeAg): HBeAg is a protein produced in the core or in the region near the core of the HB virus. A positive HBeAg result indicates active viral replication and infectivity. A negative HBeAg result may indicate low replication and infectivity, but may also mean that the virus is mutant and lacks HBeAg.
- Hepatitis B e-antibody (anti-HBe): Anti-HBe is an antibody to HBeAg. Lack of HBeAg and presence of anti-HBe in the serum is called seroconversion and may be an indication of resolving infection, but anti-HBe does not protect against HBeAg negative mutant viruses.
- HBV DNA: HBV DNA is the genetic material of the HB virus and this test is a measure of the actual viral load and replication.
What do hepatitis B test results mean?
Hepatitis B test results help determine if HBV infection is negative or positive, and if positive, whether the infection is acute or chronic, or if recovery is complete. A combination of results are considered to identify and classify HBV infection status.
The following are some interpretations of hepatitis B test results:
HBsAg
Anti-HBc
Anti-HBs
Negative
Negative
Negative
Clear of infection but susceptible, requires vaccination to protect
HBsAg
Anti-HBc
Anti-HBs
Negative
Positive
Positive
Immune due to successful recovery from past infection
HBsAg
Anti-HBc
Anti-HBs
Negative
Negative
Positive
Immune due to HBV vaccination
HBsAg
Anti-HBc
Anti-HBs
IgM anti-HBc
Positive
Positive
Negative
Positive
Acute infection that occurred within the previous 6 months
HBsAg
Anti-HBc
Anti-HBs
IgM anti-HBc
Positive
Positive
Negative
Negative
Chronic infection which may be positive or negative for HBeAg
HBsAg
Anti-HBc
Anti-HBs
Negative
Positive
Negative
Multiple possibilities such as:
- Resolved infection
- False-positive anti-HBc (susceptible to infection)
- False-negative HBsAg or anti-HBs
- Low level chronic infection
- Resolving acute infection