At a Glance
Why Get Tested?
When to Get Tested?
If you have symptoms of an infection with and/or have been exposed to HAV; if you have chronic liver disease; or if you have received the HAV vaccine
A blood sample drawn from a vein in your arm
Test Preparation Needed?
The Test Sample
What is being tested?
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 characterized 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 panel can tell your doctor that you have hepatitis, they will not tell her 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. Because hepatitis A IgM antibodies develop early in the course of infection, a positive hepatitis A IgM test is usually considered diagnostic for acute hepatitis A. A total hepatitis A antibody test detects the presence of the IgM and IgG antibodies and may help determine if you have been infected in the past and have some immunity to the disease. A test for hepatitis A IgM may be part of an acute viral hepatitis panel that may be used to determine which virus is causing symptoms when viral hepatitis is suspected.
A vaccine is available to help prevent hepatitis A. According to the CDC, cases of hepatitis A have dropped by 89% since the introduction of the hepatitis A vaccine in 1995. In 2007, just under 3000 cases of acute hepatitis A were reported, the lowest to date.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
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.
Sources Used in Current Review
(Update August 21, 2009) Lehrer J. Hepatitis A. MedlinePlus Medical Encyclopedia. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000278.htm. Accessed August 2009.
(Updated June 13, 2008) Centers for Disease Control and Prevention. FAQs for Health Professionals, Hepatitis A. Available online at http://www.cdc.gov/hepatitis/HAV/HAVfaq.htm#general through http://www.cdc.gov. Accessed August 2009.
(June 24, 2008) CDC. Statistics and Surveillance, Hepatitis A. Available online at http://www.cdc.gov/hepatitis/Statistics.htm through http://www.cdc.gov. Accessed September 2009.
(Sep. 5, 2009) Mayo Clinic Staff. Hepatitis A. Available online at http://www.mayoclinic.com/health/hepatitis-a/DS00397 through http://www.mayoclinic.com. Accessed September 2009.
Forbes BA, Sahm DF, Weissfeld AS. Bailey & Scott's Diagnostic Microbiology 12th Edition: Mosby Elevier, St. Louis, MO; 2007, Pp 764-765.
(Updated February 2009) American Academy of Family Physicians. Hepatitis A. Available online at http://familydoctor.org/online/famdocen/home/common/infections/hepatitis/897.html through http://familydoctor.org. Accessed August 2009.
Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Burtis CA, Ashwood ER and Bruns DE, eds. 4th ed. St. Louis, Missouri: Elsevier Saunders; 2006, Pp 1804-1805.
Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. McPherson RA and Pincus MR, eds. Philadelphia: 2007, Pp 271.
Sources Used in Previous Reviews
Clinical Chemistry: Principles, Procedures, Correlations. Michael L. Bishop, Janet L. Duben-Engelkirk, Edward P. Fody. Lipincott Williams & Wilkins, 4th Edition.