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Test Catalog

Test ID: HAIGM    
Hepatitis A IgM Antibody, Serum

Useful For Suggests clinical disorders or settings where the test may be helpful

Diagnosis of acute or recent hepatitis A infection

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Hepatitis A virus (HAV) is endemic throughout the world, occurring most commonly, however, in areas of poor hygiene and low socioeconomic conditions. The virus is transmitted primarily by the fecal-oral route, and it is spread by close person-to-person contact and by food- and water-borne epidemics. Outbreaks frequently occur in overcrowded situations and in high-density institutions and centers, such as prisons and health care or day care centers. Viral spread by parenteral routes (eg, exposure to blood) is possible but rare, because infected individuals are viremic for a short period of time (usually <3 weeks). There is little or no evidence of transplacental transmission from mother to fetus or transmission to newborn during delivery.

 

Serological diagnosis of acute viral hepatitis A depends on the detection of specific anti-HAV IgM. Its presence in the patient's serum indicates a recent exposure to HAV. HAV-specific IgM antibody level becomes detectable in the blood by 4 weeks after infection, persisting at elevated levels for about 2 months before declining to undetectable levels by 6 months. They rarely persist beyond 12 months after infection.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Negative 

See Viral Hepatitis Serologic Profiles in Special Instructions.

Interpretation Provides information to assist in interpretation of the test results

This assay detects the presence of hepatitis A virus (HAV)-specific IgM antibody in serum.

 

Negative results indicate either 1) inadequate or delayed anti-HAV IgM response after known exposure to HAV, or 2) absence of acute or recent hepatitis A.

 

Equivocal results may be seen in early acute hepatitis A associated with rising anti-HAV IgM levels or recent hepatitis A infection associated with declining anti-HAV IgM levels. Retesting for both anti-HAV IgM (HAIGM / Hepatitis A IgM Antibody, Serum) and anti-HAV IgG (HAIGG / Hepatitis A IgG Antibody, Serum) in 2 to 4 weeks is recommended to determine the definitive HAV infection status.

 

Positive results indicate acute or recent (<6 months) hepatitis A infection. As required by laws in almost all states, positive anti-HAV IgM test results must be urgently reported to state health departments for epidemiologic investigations of possible outbreak transmission.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Testing too early (<2 weeks) after exposure to hepatitis A virus (HAV) may yield negative anti-HAV IgM results.

 

False-positive results may be due to presence of cross-reactive antibodies from other viral infection or underlying illnesses (such as non-Hodgkin lymphoma). Positive results should be correlated with patient's clinical history and epidemiologic exposure. 

 

The presence of heterophilic antibodies and human antimouse antibodies (in patients who have received preparations of mouse monoclonal antibodies for diagnosis or therapy) in serum may interfere with the assay and cause erroneous results (false-positive or false-negative).

 

Performance characteristics have not been established for the following specimen characteristics:

-Grossly icteric (total bilirubin level of >20 mg/dL)

-Grossly hemolyzed (hemoglobin level of >500 mg/dL)

-Grossly lipemic (triolein >3,000 mg/dL)

-Containing particulate matter

-Heat-inactivated

-Cadaveric specimens

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. 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 Morb Mortal Wkly Rep. 2006;55(RR7):1-23

2. Nainan OV, Xia G, Vaughan G, Margolis HS: Diagnosis of hepatitis A infection: a molecular approach. Clin Microbiol. Rev 2006;19:63-79

3. de Paula VS: Laboratory diagnosis of hepatitis A. Future Virology. 2012;7(5):461-472

Special Instructions Library of PDFs including pertinent information and forms related to the test