Hepatitis A Antibody Test-Why am I having this test?

The hepatitis A antibody test is done:

• To diagnose hepatitis A infection.
• To check for infection, if there is concern that you have been exposed to hepatitis A.
• To find the cause of long-term (chronic) liver disease or abnormal results on a liver function test.
• To see if you are already protected from (immune to) hepatitis A.
• To see if you need the hepatitis A vaccine to protect you from future infection.

What is being tested?

The hepatitis A antibody test looks for hepatitis A antibodies. These are infection-fighting proteins that are produced by your body’s defense (immune) system in response to being infected with the hepatitis A virus (HAV). These antibodies are also produced after you receive the hepatitis A vaccine.

Different types of HAV antibodies may be present in your blood, depending on how long it has been since infection or vaccination occurred. The different types of antibodies include:

• IgM (immunoglobulin M) antibodies. These appear first.
• IgG (immunoglobulin G) antibodies. These appear later.

What kind of sample is taken?

A blood sample is required for this test. It is usually collected by inserting a needle into a blood vessel.

How are the results reported?

Your test results will be reported as either positive or negative for the presence of each antibody in your blood. Positive means that you have the antibody, and negative means that you do not have the antibody. For this test, normal results are:

• Negative for all types of hepatitis A antibodies (except the ones that show that you are protected by the HAV vaccine).

Sometimes, the test results may report that a condition is present when it is not present (false-positive result).

Sometimes, the test results may report that a condition is not present when it is present (false-negative result).

What do the results mean?

Negative results

Results that are negative for all types of hepatitis A antibodies (except the ones that show that you are protected by the HAV vaccine) may mean that you do not have hepatitis A.

• Be aware, however, that the test could give you a false-negative result even if infection is present. This is because it can take up to 4 weeks from the time of infection until HAV IgM antibodies appear in your blood. If your health care provider suspects that you have hepatitis A infection, you may be asked to repeat the test.

Combined negative and positive results

The following hepatitis A antibody test results may indicate several health conditions. Possible test result combinations include:

• Positive for HAV IgM antibodies but negative for HAV IgG antibodies. This means that you have an active hepatitis A infection.
• Negative for HAV IgM antibodies but positive for HAV IgG antibodies. This means that one of these is true for you:
  • You have long-term (chronic) HAV infection.
  • You were exposed to HAV in the past but no longer have an active infection.
  • You have received protection against HAV from a HAV vaccine.

Talk with your health care provider about what your results mean.

Questions to ask your health care provider

Ask your health care provider, or the department that is doing the test:

• When will my results be ready?
• How will I get my results?
• What are my treatment options?
• What other tests do I need?
• What are my next steps?

Summary

• The hepatitis A antibody test checks whether hepatitis A antibodies are present in your blood. These antibodies are proteins that your body produces in response to the hepatitis A virus (HAV), or the hepatitis A vaccine.
• A blood sample is required for this test.
• Your test results will be reported as either positive or negative for the presence of each antibody in your blood.
• Talk with your health care provider about what your results mean.