At a Glance
Why Get Tested?
To diagnose an infection with hepatitis A or to evaluate the need for, or the response to, hepatitis A vaccination
When to Get Tested?
If you have symptoms of an infection with or have been exposed to the hepatitis A virus
A blood sample drawn from a vein in your arm
The Test Sample
What is being tested?
Hepatitis A antibody is produced in response to an infection with the hepatitis A virus. Hepatitis A is a highly contagious liver infection caused by the hepatitis A virus (HAV). It is one of several various causes of hepatitis, a condition characterised by inflammation and enlargement of the liver. Hepatitis A is one of five "hepatitis viruses" identified so far, including B, C, D, and E that are known to cause the disease.
Hepatitis A is spread through food or water contaminated with the virus or by coming in contact with an infected person. While hepatitis A can cause a severe, acute disease, it does not cause a chronic infection as do some of the other hepatitis viruses. If you are exposed to hepatitis A, your immune system produces antibodies in response to the virus. This test detects hepatitis A antibodies in the blood.
While hepatitis has many different causes, the signs and the symptoms are the same. In hepatitis, the liver is damaged and unable to function normally. It cannot process toxins or waste products such as bilirubin for their removal from the body. During the course of the disease, bilirubin and liver enzyme levels in the blood can increase. While tests such as bilirubin or a liver function tests can tell your doctor that you have hepatitis, they will not tell s/he what is causing it. Antibody tests for hepatitis viruses may help determine the cause.
If you are exposed to hepatitis A, your body will first produce hepatitis A IgM antibodies. These antibodies typically develop 2 to 3 weeks after first being infected and persist for about 2 to 6 months. Hepatitis A IgG antibodies are produced within 1 to 2 weeks of the IgM antibodies and usually persist for life. Hepatitis A IgM antibodies develop early in the course of infection. The presence of hepatitis A IgM antibodies suggests acute hepatitis A but is only diagnostic if taken in the right clinical context. A positive hepatitis A IgM together with the presence of grossly abnormal liver function tests demonstrating hepatitis, the presence of symptoms such as nausea, fever, malaise, abdominal discomfort or a history of significant contact with a confirmed case is consistent with acute Hepatitis A. A positive Hepatitis A IgM is also seen in patients who have received the Hepatitis A vaccine in the days or weeks prior to testing and therefore the result should not be interpreted as evidence of acute disease. Testing for immunity to Hepatitis A can also be performed. Acute hepatitis is also caused by a number of other infectious and non-infectious agents and the choice of tests to use depends on the clinical scenario.
How is the sample collected for testing?
A blood sample is taken by needle from a vein in the arm.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.