Hepatitis A IgM Antibody, Serum

CPT CODE:

USEFUL FOR:

Diagnosis of acute or recent hepatitis A infection

SPECIMEN REQUIRED:

Draw blood in a plain, red-top tube(s) or a serum gel tube(s). Spin down, remove serum from clot within 24 hours, and send 2 mL of serum frozen in plastic vial. Note:    Draw date is required on request form for processing.

TRANSPORT TEMPERATURE:

Frozen\Refrig <7 days OK\Ambient <24 hours OK

CLINICAL INFORMATION:

Hepatitis A virus (HAV) is endemic throughout the world, occurringmost commonly, however, in areas of poor hygiene and lowsocioeconomic 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 serumindicates a recent exposure to HAV. Anti-HAV IgM becomes detectable in the blood within 2 weeks after infection, persisting atelevated levels for about 2 months before declining to undetectablelevels by 6 months. However, sensitive immunoassays mayoccasionally detect anti-HAV IgM for up to 1 year after acute hepatitis A.

CLINICAL INTERPRETATION:

A positive result indicates acute or recent (<6 months) hepatitis Ainfection. As required by laws in almost all states, positive anti-HAV IgM test results must be urgently reported to state health departmentsfor epidemiologic investigations of possible outbreak transmission.
A negative result may indicate either 1) inadequate or delayed HAVIgM response after known exposure to HAV, or 2) absence of acuteor recent hepatitis A.
Borderline anti-HAV IgM test results may be seen in: 1) early acutehepatitis A associated with rising antibody levels,  2) recent hepatitis A associated with declining levels, or 3) cross-reactivitywith nonspecific antibodies (ie, false-positive results). Retesting of both anti-HAV IgM (#8342 "Hepatitis A IgM Antibody, Serum") and anti-HAV total (#83330 "Hepatitis A Total Antibodies, Serum") in 2 to 4 weeks is recommended to determine the definitive HAV infection status.

REFERENCE VALUES:

Negative 

See "Viral Hepatitis Serologic Profile" in Special Instructions.