Hepatitis B Testing
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When you have risk factors for HBV infection or when you have signs and symptoms of hepatitis, such as jaundice or unexplained elevated blood levels of alanine aminotransferase (ALT), a liver-associated enzyme; when you have a condition that requires chemotherapy or drugs that suppress your immune system; when you are being treated for HBV or hepatitis C (HCV); when it is unclear whether you have immunity and your healthcare practitioner is considering giving you the hepatitis B vaccine
A blood sample drawn from a vein in your arm
None
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How is it used?
The main uses for hepatitis B virus (HBV) tests include:
- To determine whether acute signs and symptoms, such as jaundice, fever and fatigue, are due to hepatitis B infection; two tests, hepatitis B surface Ag and hepatitis B core antibody IgM, may be performed as part of an acute viral hepatitis panel along with tests for hepatitis A (HAV) and hepatitis C (HCV) to determine which virus may be causing the infection.
- To diagnose chronic HBV hepatitis
- To monitor chronic hepatitis B infection and its treatment
- To detect a previous, resolved hepatitis B infection, in a person who is immune compromised (when the virus can become reactivated) or who has hepatitis C and in whom treatment is planned
Some of the secondary reasons to perform testing include: to screen for hepatitis B infection in at-risk populations or in blood donors, to determine if someone is a carrier, to detect a resolved infection, and to determine if immunity has developed due to vaccination.
Generally, one set of tests is used as an initial panel of tests to detect HBV infection or to determine the cause of acute symptoms while another set of tests may be used after a diagnosis is made to monitor possible progression of the disease, to detect chronic infection, and/or to determine carrier status.
The following table summarizes the set of tests typically used for initial testing:
Test Description Use and Comments Hepatitis B surface antigen (HBsAG) Detects protein that is present on the surface of the virus To screen for, detect, and help diagnose acute and chronic HBV infections; earliest routine indicator of acute hepatitis B and frequently identifies infected people before symptoms appear; undetectable in the blood during the recovery period; it is the primary way of identifying those with chronic infections, including "HBV carrier" state. Hepatitis B surface antibody (anti-HBs) Detects antibody produced in response to HBV surface antigen Used to detect previous exposure to HBV; it can also develop from successful vaccination so it is used to determine the need for vaccination (if anti-HBs is absent) or to determine if a person has recovered from an infection and is immune (cannot get the infection again). Total anti-hepatitis B core (anti-HBc, IgM and IgG) Detects both IgM and IgG antibodies to hepatitis B core antigen Can be used to help detect acute and chronic HBV infections; the IgM antibody is the first antibody produced after infection with HBV; IgG antibody is produced in response to the core antigen later in the course of the infection and usually persists for life. Anti-hepatitis B core (anti-HBc, IgM) Detects only the IgM antibody to the hepatitis B core antigen Used to detect acute infections; may be included in initial testing, e.g., when done as part of an acute viral hepatitis panel The following table summarizes tests that may be used as follow-up after initial tests detect an HBV infection:
Test Description Use and Comments Hepatitis B e-antigen (HBeAG) Detects protein produced and released into the blood Often used as a marker of ability to spread the virus to other people (infectivity); it may also be used to monitor the effectiveness of treatment. However, there are some types (strains) of HBV that do not make e-antigen; these are especially common in the Middle East and Asia. In areas where these strains of HBV are common, testing for HBeAg is not very useful to determine whether the virus can be spread to others. Anti-hepatitis B e antibody (Anti-HBe) Detects antibody produced by the body in response to the hepatitis B "e" antigen Used to monitor acute infections in those who have recovered from acute hepatitis B infection; anti-HBe will be present along with anti-HBc and anti-HBs. Hepatitis B viral DNA Detects hepatitis B viral genetic material in the blood A positive test indicates that the virus is multiplying in a person's body and that person is contagious. The test is often used to monitor the effectiveness of antiviral therapy in people with chronic HBV infections. Hepatitis B virus resistance mutations Detects mutations in the particular virus causing a person's infection that allows the virus to be resistant to treatments (reverse transcriptase inhibitors) Helps to select appropriate treatment, especially in people who have been treated previously or in those who are not responding to treatment While the tests described above are specific for HBV, other liver tests such as aspartate aminotransferase (AST), alanine aminotransferase (ALT), and gamma-glutamyl transferase (GGT) may be used to monitor the progress of the disease. In some cases, a liver biopsy may be performed to evaluate how much damage has occurred to the liver.
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When is it ordered?
Hepatitis B tests may be ordered when someone has signs and symptoms associated with acute hepatitis to determine if they are due to infection with HBV. Some of these include:
- Fever
- Fatigue
- Loss of appetite
- Nausea, vomiting
- Abdominal pain
- Dark urine
- Pale stools
- Joint pain
- Jaundice
Hepatitis B tests may be done as follow up when routine tests results such as ALT and/or AST are elevated. Sometimes acute forms of hepatitis may be detected this way since they may cause only mild symptoms that can be confused with the flu. Chronic hepatitis more often has no symptoms and is more commonly detected when routine test results are abnormal.
A test for hepatitis B surface antigen (HBsAg) may be used for screening when someone falls into one of the high-risk categories for chronic hepatitis B. Joint guidelines from the Centers for Disease Control and Prevention (CDC) and American College of Physicians were published in December 2017 and recommend the following groups be tested for HBsAg:
- People born in areas of the world that have a greater than 2% prevalence of HbsAg (for example, much of Asia and Africa)
- People born in the U.S. but who were not vaccinated and whose parents are from an area with greater than 8% prevalence of HbsAg
- Men who have sex with men
- People who have elevated liver enzymes (ALT and AST) with no known cause
- People with certain medical conditions that require that their immune system be suppressed, such as organ transplant recipients
- People with end-stage kidney disease
- Pregnant women
- Infants born to women with hepatitis B infection
- People who live with a person with hepatitis B infection (household contact) or who have sexual partners with HBV
- Those infected with HIV or HCV
- Individuals living in correctional facilities
- People who inject drugs
- People who donate blood, plasma, tissue, organs or semen
When hepatitis B tests are used to monitor people with chronic hepatitis B infections, they may be performed on a regular basis. Hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg), often along with HBV DNA, are usually measured about every 6 months to a year since, in some people, HBeAg (and, less commonly, HBsAg) will go away on their own. In those who are being treated for chronic HBV, HBeAg and HBV DNA tests can be used to determine whether the treatment is successful.
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What does the test result mean?
The tests for hepatitis B may be ordered individually but are often ordered in some combination, depending on the reason for testing. Results of the tests are typically evaluated together. Sometimes the meaning of one result depends on the result of another test. However, not all tests are performed for all people.
The table below summarizes possible interpretations of some common patterns of results.
Initial Tests Follow-up Tests Hep B surface antigen (HBsAg) Hep B surface antibody (Anti-HBs) Hep B core antibody Total (Anti-HBc IgG+IgM) Hep B core antibody (Anti-HBc IgM) Hep B e antigen (HBeAg)* Hep B e antibody (Anti-HBe) HBV DNA Possible Interpretation / Stage of Infection Negative Negative Negative Negative Not performed Not performed Not performed No active or prior infection; not immune — may be good candidate for vaccine; possibly in the incubation stage Negative Positive Negative Not performed Not performed Not performed Not performed Immunity due to vaccination Negative Positive Positive Not performed Not performed Not performed Not performed Infection resolved; virus can reactivate if immune system suppressed Positive Negative Positive or Negative Positive Positive or negative Negative Detected Acute infection, usually with symptoms; contagious; could also be flare of chronic infection Negative Negative Positive Positive Negative* Positive None detected Acute infection is resolving (convalescent) Positive Negative Positive Negative Positive* or Negative Negative or Positive Detected Usually indicates an active chronic infection (liver damage likely) Positive Negative Positive Negative Negative Positive None detected or detected at very low level Chronic infection but low risk of liver damage — carrier state *Note: There are some types (strains) of HBV that do not make e-antigen. In areas where these strains of HBV are common (in the Middle East and Asia), testing for HBeAg is not very useful. In these cases, a negative HbeAg result does not necessarily mean that the person is not infectious; it may be that the person is infected with a strain that does not make the e-antigen.
Monitoring treatment of chronic infection: If the results from initial and follow-up testing indicate that a person has chronic hepatitis B, then the individual may be treated with medication and the effectiveness of that treatment may be monitored using the tests for HBe and HBs antigen and antibody and HBV DNA:
- If HBsAg becomes negative and anti-HBs becomes positive during treatment, this usually indicates that treatment is effective and that treatment can be discontinued after an additional 6-12 months.
- If HBeAg becomes negative and anti-HBe becomes positive during treatment, this usually indicates that it is effective and that treatment may be discontinued after an additional 6-12 months, although the virus may reappear later, so continued monitoring is needed.
- HBV DNA measures the amount of virus present in the blood. A high result usually means that the virus is actively replicating and that treatment is not effective. A low result or one that is reported as below a lower limit (none detected) means the virus is not present or is present in such low numbers that it cannot be detected. This usually indicates that the therapy is effective in controlling replication of the virus; however, the virus may reappear if the treatment is stopped.
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Is there anything else I should know?
Even if you don't have symptoms, an HBV infection can damage your liver and you can spread the infection to others. For this reason, it is important to get tested if you think you have been exposed to HBV.
Blood banks screen all donated blood for the hepatitis B virus (HBV DNA), hepatitis B surface antigen (HbSAg), and hepatitis B core antibody (anti-HBc). Donors are notified of any confirmed positive reactions. People who receive a notice regarding possible infection with hepatitis B after donating should visit their healthcare provider for further testing. The healthcare practitioner will order additional tests to make a proper diagnosis and determine if treatment is necessary.
If exposed to HBV and you haven't been vaccinated, an infection can be avoided by getting a shot of hepatitis B immune globulin (HBIG) within 24 hours and typically you will also be given the first dose of the hepatitis B vaccine.
A test is available to determine the specific type (strain) of hepatitis B virus that is causing a person's infection. This is called HBV genotyping. However, this testing is currently mainly used in research settings and not for clinical purposes.
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If it is possible that I have an HBV infection, will I need to have all these tests done?
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Should I get the HBV vaccine?
The Centers for Disease Control and Prevention (CDC) recommends that adults in high-risk groups get vaccinated. Some of these groups include people:
- In close contact with someone who has hepatitis B
- Who undergo dialysis
- With chronic liver or kidney disease
- With HIV or who seek treatment for other sexually transmitted diseases or drug treatment
- Who travel to countries where hepatitis B is common
- Who are healthcare workers with potential exposure to HBV
Unless there is something in your medical history to the contrary, it is prudent to get the series of vaccinations. Babies, children and adolescents are routinely given the series of shots; if you have already been vaccinated, you probably are protected for many years, perhaps for life, and will not usually need to get the vaccine again.
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How is hepatitis B treated?
There is no specific treatment for acute hepatitis B infections. Symptoms are usually treated with supportive care. This usually involves making sure that you are getting plenty of rest and enough fluids and nutrition by eating and drinking small amounts several times a day.
Chronic forms of hepatitis B may be treated with antiviral medications such as interferon, entecavir, tenofovir, lamivudine, and adefovir. However, some antiviral drugs can have serious side effects and not all people need to be treated. Often, people with chronic hepatitis will be closely monitored to see if they develop cirrhosis or liver cancer. It is important to talk to your healthcare provider about your treatment options and the risks and benefits of those currently available.
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What is hepatitis D (HDV) and how is it associated with hepatitis B?
Hepatitis D (HDV) is another virus that can cause liver infections, but only if hepatitis B is also present. A person may become infected with both viruses at the same time (a co-infection) or may first be infected with hepatitis B and then become infected with HDV (a superinfection). In the U.S., the incidence of HDV is low. There is no vaccine for HDV, but since it causes infections only in the presence of HBV, it may be prevented with the HBV vaccine.