Synonym

• Antibody Hepatitis A Virus-IgG
• Antibody Hepatitis A Virus-IgM
• Anti-HAV IgG
• Anti-HAV IgM
• HAV serology
• HAVAb-IgM

Tubes

• Red or tiger top tube recommended
• Lavender or green top tube accepted at some laboratories
• 5-7 mL of venous blood

Additional information

• Handle sample gently to prevent hemolysis
• Send the sample to lab within 2-4 hrs

Info

• Hepatitis A antibody testing detects the presence of antibodies specific to hepatitis A virus (IgM, IgG) in the blood
• Hepatitis A virus (HAV) is an enterovirus of the picornaviridae family, and a very common cause of hepatitis worldwide (very common in the third world, less common in developed countries)
• IgM positivity is consistent with acute infection
• IgG positivity is consistent with prior infection
• There is immunization available for Hepatitis A, most typically used in individuals before travel to third world countries

Clinical

• The indications of Hepatitis A antibodies test include:
• Evaluation of a person with signs and symptoms of acute hepatitis or other suspicion of HAV infection
• Screen individuals, who are at risk of exposure such as:
• Family members of infected persons
• Persons traveling to countries where hepatitis A is common
• People in long-term residential facilities, day care centers for children, or correctional facilities
• Military personnel stationed abroad, especially in developing countries
• People who may come into contact with HAV at work
• Pregnant women
• Sex contacts of infected persons
• Men who have sex with men (CDC)
• Assists in differentiating recent infection (IgM) from prior exposure (IgG) to HAV
• Assists in the epidemiological studies to measure the prevalence of previous infection
• To detect the presence of previous HAV infection before administration of the HAV vaccine (as the vaccine would not be beneficial)
• To detect if the subject has responded to the HAV vaccine after completing two doses
• The primary mode of transmission of HAV infection is by fecal-oral route under poor personal hygiene or inadequate sanitary conditions, consumption of uncooked or raw food, and very rarely, through parenteral transmission (blood transfusion or organ transplantation)
• The average incubation period is 28 days, but ranges from 15-50 days. HAV infection is most contagious before symptoms and/or jaundice occurs
• Most people with HAV infection (70%) do not develop overt disease and are asymptomatic (especially children). These asymptomatic infected persons can still transmit HAV
• The onset of HAV infection is typically rapid in onset, with symptoms developing 2-6 weeks after infection and usually resolving within 2 months (rarely longer). About 15% of people infected with hepatitis A may have intermittent symptoms for up to 6-9 months
• Clinical findings of HAV infection include
• Nausea and vomiting
• Loss of appetite
• Diarrhea, especially in children
• Fatigue
• Fever
• Jaundice (children: 10%, adults: 70–80%)
• Abdominal pain
• Hepatomegaly
• If jaundiced, usually will have dark brown urine and pale stools
• HAV does not usually cause chronic hepatitis, cirrhosis, or carrier states, however approximately 1% of patients can develop a potentially fatal fulminant hepatitis more frequently in:
• Individuals with underlying liver disease
• Elderly
• Pregnant women
• HAV infected persons develop antibodies specific to HAV (anti-HAV), which include:
• Immunoglobulin M antibodies to the capsid proteins of HAV (IgM anti-HAV) detectable 5-10 days before the onset of symptoms and persist for 6 months. IgM antibodies reflect recent acute infection with HAV
• Immunoglobulin G antibodies (IgG anti-HAV) that appear 4 weeks later than IgM and persist for years. IgG antibodies reflect infection which occurred months to years before, and provide lifelong protection against Hepatitis A
• IgG antibodies are seen after administration of immune globulin and after successful seroconversion following vaccination

Additional information

• Diagnosis of acute Hepatitis A is useful such that
• Treatment and monitoring of the infected person can be initiated
• Protective measures can be taken to prevent disease spread, particularly for those who have close patient contact
• Hepatitis A in those patients who are HIV infected, can prolong the duration and increase the level of HAV viremia, enhancing HAV-related liver abnormalities
• HAV infection that occurs as epidemics, is usually referable to a common source such as contaminated water or the ingestion of shellfish containing the virus
• About 50-70% of adults in the U.S. have antibodies to HAV
• Related laboratory tests include:
• -Glutamyltranspeptidase
• Alanine aminotransferase
• Aspartate aminotransferase
• Hepatitis B and C antigens and antibodies
• Liver biopsy and liver scan
• Polymerase chain reaction (PCR) test for HAV
• Prothrombin time (PT)
• Serum albumin and globulin
• Serum alkaline phosphatase
• Serum and urine bilirubin

Nl Result

Hepatitis A virus markers:

• HAV-Ab/IgM: Negative/Nonreactive
• HAV-Ab/IgG: Negative/Nonreactive

Method: ELISA, Micro enzyme immunoassay (MEIA), PCR or recombinant immunoblot assay, or RT-PCR

High Result

A positive result for HAV-Ab IgM is abnormal and consistent with acute Hepatitis A; whereas a positive IgG indicates remote infection or seroconversion due to successful vaccination.

HAV-Ab IgM

• HAV-Ab IgM is typically present 5-10 days before the onset of symptoms and persists for 6 months
• Clinically useful as this is positive by the time a patient presents with symptoms of acute hepatitis

HAV-Ab IgG

• HAV-Ab IgG is typically present about 4 weeks after onset of symptoms (8–12 wks after infection) and often remains detectable for life
• Clinically useful in indicating that the patient has immunity to hepatitis A (felt to be lifelong immunity when in response to actual HAV infection)
• Goal of immunization for Hepatitis A is detectable HAV-Ab IgG which indicates that immunity is present (duration of immunity related to immunization is unknown)

Low Result

A negative result is useful as a screening test in low probability patients. In patients with a clinical scenario likely to be hepatitis A, a false negative result must be considered.

References

• Beyazit Y et al. Acute pericarditis and renal failure complicating acute hepatitis A infection. South Med J. 2006 Jan;99(1):82-4.
• Centers for Disease Control: Prevention of Hepatitis A Through Active or Passive Immunization. May 19, 2006 / 55(RR07);1-23. [Homepage on the Internet]. Last reviewed on May 19, 2006. Last accessed on January 29, 2007. Available at URL: http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5507a1.htm
• Centers for Disease Control: Viral Hepatitis A – Fact Sheet [Homepage on the Internet]. Last reviewed on December 8, 2006. Last accessed on January 29, 2007. Available at URL: http://www.cdc.gov/ncidod/diseases/hepatitis/a/fact.htm
• Chelibek R et al. [Seroprevalence of antibodies against hepatitis A virus and hepatitis B virus in nonvaccinated adult population over 40 years of age] [Article in Czech]. Epidemiol Mikrobiol Imunol. 2006 Aug;55(3):99-104.
• Fujiwara K et al. Do high levels of viral replication contribute to fulminant hepatitis A?Liver International Volume 25 Issue 1 Page 194 - February 2005 doi:10.1111/j.1478-3231.2004.0981.x Volume 25 Issue 1
• Godoi ER et al. Loss of hepatitis A virus antibodies after bone marrow transplantation. Bone Marrow Transplant. 2006 Jul;38(1):37-40. Epub 2006 May 22.
• Jothikumar N et al. Development and evaluation of a broadly reactive TaqMan assay for rapid detection of hepatitis A virus. Appl Environ Microbiol. 2005 Jun;71(6):3359-63.
• Laboratory Corporation of America®. Hepatitis A Antibody, IgM. [Homepage on the internet]©2003. Last updated on August 23, 2006. Last accessed on January 29, 2007. Available at URL: http://www.labcorp.com/datasets/labcorp/html/chapter/mono/hc000100.htm
• LabTestsOnline®. Hepatitis A. [Homepage on the Internet]©2001-2006. Last reviewed on February 25, 2005. Last accessed on January 29, 2007. Available at URL: http://www.labtestsonline.org/understanding/analytes/hepatitis_a/test.html
• Laurence JC. Hepatitis A and B immunizations of individuals infected with human immunodeficiency virus. Am J Med. 2005 Oct;118 Suppl 10A:75S-83S.
• Roque-Afonso AM et al. Diagnostic relevance of immunoglobulin G avidity for hepatitis A virus. J Clin Microbiol. 2004 Nov;42(11):5121-4.
• UTMB Laboratory Survival Guide®. HEPATITIS A VIRUS ANTIBODY (Total). [Homepage on the Internet]© 2006. Last reviewed on March 6, 2003. Last accessed on January 29, 2007. Available at URL: http://www.utmb.edu/lsg/LabSurvivalGuide/micro/HEPATITIS%20A%20ANTIBODY.html