At a Glance
Why Get Tested?
To help diagnose the cause of acute hepatitis; as part of a viral hepatitis panel to identify the type of hepatitis virus causing an infection; sometimes to evaluate the need for the hepatitis A vaccine
When to Get Tested?
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. This test detects antibodies in the blood that are produced by the immune system in response to a hepatitis A infection.
Hepatitis A is one of five "hepatitis viruses" identified so far, including B, C, D, and E, that are known to cause the disease. While hepatitis A can cause a severe, acute disease that typically lasts 1 to 2 months, it does not cause a chronic infection as do some of the other hepatitis viruses.
Hepatitis A is spread, most commonly, from person-to person through stool (fecal) contamination or by ingesting food or water contaminated by the stool of an infected person (a foodborne illness). Recognized risk factors for hepatitis A include close contact with an infected person, international travel, household or personal contact with a child who attends a child care center, household or personal contact with a newly arriving international adoptee, a recognized foodborne outbreak, men who have sex with men, and use of illegal drugs.
Although there are many causes of hepatitis, the symptoms remain 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 a health practitioner that someone has hepatitis, they do not identify the cause. Antibody tests for hepatitis viruses may help determine the cause.
There are two different classes of hepatitis A antibody that may be tested, IgM and IgG. When a person is exposed to hepatitis A, the body first produces hepatitis A IgM antibodies. These antibodies typically develop 2 to 3 weeks after first being infected (and are detectable before the onset of symptoms) and persist for about 3 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 a current or recent infection of hepatitis A. This test may be done as part of an acute viral hepatitis panel used to determine which virus is causing symptoms when viral hepatitis is suspected.
- An HAV IgG test may be used to help determine if a person has been infected in the past and has some immunity to the disease.
- A total hepatitis A antibody test detects the presence of both the IgM and IgG antibodies, thus can identify current and past infections.
A vaccine that prevents hepatitis A has been available since 1995. Historically, infection rates varied cyclically, with nationwide increases every 10-15 years. However, rates have declined in general since the vaccine was introduced. In 2010, the number of acute hepatitis A cases reported nationwide declined by approximately 53% from about 3,600 in 2006.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into 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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Sources Used in Current Review
Centers for Disease Control and Prevention. FAQs for Health Professionals: Hepatitis A. Available online at http://www.cdc.gov/hepatitis/HAV/HAVfaq.htm through http://www.cdc.gov. Accessed July 27, 2013.
Center for Disease Control and Prevention. Statistics and Surveillance: Hepatitis A. Available online at http://www.cdc.gov/hepatitis/statistics/2010surveillance/Commentary.htm#analysesI through http://www.cdc.gov. Accessed July 27, 2013.
Mayo Clinic. Hepatitis A. Available online at http://www.mayoclinic.com/health/hepatitis-a/DS00397 through http://www.mayoclinic.com. Accessed July 27, 2013.
National Digestive Diseases Information Clearinghouse (NDDIC). Viral Hepatitis: A through E and Beyond. Available online at http://digestive.niddk.nih.gov/ddiseases/pubs/viralhepatitis/index.aspx#hepa through http://digestive.niddk.nih.gov. Accessed July 27, 2013.
Fischbach, F.T. (2004). A Manual of Laboratory & Diagnostic Tests. 7th Edition., Lippincott Williams & Wilkins, Philadelphia.
(August 29, 2013) Gilroy R. Hepatitis A. Medscape Reference article. Available online at http://emedicine.medscape.com/article/177484-overview through http://emedicine.medscape.com. Accessed August 2013.
(May 19, 2006) Centers for Disease Control and Prevention. Prevention of Hepatitis A Through Active or Passive Immunization. Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 55(RR07);1-23. Available online at http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5507a1.htm through http://www.cdc.gov. Accessed August 2013.
Fiore AF, Wasley A, Bell, BP. Prevention of Hepatitis A Through Active or Passive Immunization. Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 2006;55(RR07);1-23.
(Updated Apr 11, 2013) Virginia Department of Public Health. Hepatitis A Factsheet. Available online at http://www.vdh.state.va.us/Epidemiology/factsheets/Hepatitis_A.htm through http://www.vdh.state.va.us. Accessed February 2014.
(©2014) World Health Organization. Hepatitis A. Available online at http://www.who.int/csr/disease/hepatitis/whocdscsredc2007/en/index1.html through http://www.who.int. Accessed February 2014.
Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. McPherson R, Pincus M, eds. Philadelphia, PA: Saunders Elsevier: 2011, Pp 305, 1058-1059.
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.
(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.