What is Hepatitis A Virus Antibody - IGM /ANTI HAV IGM?

Also Known As: Viral Hepatitis A Antibody, HAV Immunity Determination, HAV Vaccination Status, Hep A Vaccination Status, Hepatitis A Antibody, HAV-Ab IgM, HAV-Ab IgG, HAV-Ab Total, Anti-HAV

Formal Name: Viral Hepatitis A Antibody

Hepatitis A is a viral infection that causes inflammation and other problems in the liver. Hepatitis A testing detects evidence of a current or past hepatitis A infection.

Testing is performed on a sample of a patient’s blood. Hepatitis A testing may be used to diagnose hepatitis A and assess whether a person has immunity to this disease.

The purpose of hepatitis A testing is to determine if a person has been infected by the hepatitis A virus (HAV).
The hepatitis A virus is highly contagious, and infection can cause hepatitis, a condition characterized by inflammation and enlargement of the liver. There are several viruses that can cause hepatitis. Some hepatitis viruses cause only short-term infections called acute disease, while others can cause long-term infections known as a chronic diseases.

Hepatitis A is typically a sudden, acute infection that lasts a few weeks to several months. In most cases, this virus does not cause chronic infection. In rare cases, though, Hepatitis A can be severe and cause liver damage or liver failure.

This virus is spread through fecal-oral transmission, which means that a person contracts the disease when they ingest traces of the feces, also called stool, of a person infected with hepatitis A. Most often, the transmission of hepatitis A occurs through consuming unwashed food or water that has been contaminated.

A doctor may order hepatitis A testing for several purposes:

• Diagnose current infection: Doctors use hepatitis tests to diagnose the cause of hepatitis in patients with signs and symptoms of this disease.
• Assess immunity: After a person recovers from a hepatitis A infection, they become immune to future infections due to the development of protective antibodies. Hepatitis A testing may show that a person has developed protective antibodies to hepatitis A after recovering from a past infection or because they previously received a hepatitis A vaccination.

What does the test measure?

To determine if viral hepatitis is caused by the hepatitis A virus, hepatitis A testing looks for certain antibodies. Antibodies are substances made by the immune system in response to infection with a virus such as hepatitis A.

Hepatitis A testing looks for two types of antibodies. Antibodies are part of the body’s protective response to a viral infection, and hepatitis A virus antibodies may be measured by a few different tests:

• Hepatitis A immunoglobulin M (IgM anti-HAV) antibody test: When a person is first infected with hepatitis A, the body produces IgM anti-HAV antibodies. These antibodies are usually detectable from two weeks after symptoms begin to around six months later.
• Hepatitis A immunoglobulin G (IgG anti-HAV) antibody test: The IgG anti-HAV antibody test detects IgG antibodies that develop later in the course of the disease. IgG antibodies are detectable in the body for life, providing protection against a future hepatitis A virus infection. The IgG anti-HAV test is used to detect past HAV infections and may occasionally be used to determine if an individual has developed immunity from a previous infection or vaccination.
• Total hepatitis A antibody test: The total HAV antibody test detects both IgM and IgG antibodies and thus is used to identify both current and past infections.

Although testing the blood for HAV antibodies is the gold standard for identifying a hepatitis A infection, other tests may be ordered that instead look for the genetic material of the hepatitis A virus. This type of testing, also called nucleic acid amplification testing (NAAT), can detect traces of hepatitis A in a patient’s stool, blood, body fluids, and liver tissue.

In many cases, specific hepatitis A testing occurs along with or after blood tests that measure liver function. These tests may include a broad panel of tests, called a liver panel. The measurements in a liver panel can provide information about liver function and inflammation. While these tests can suggest viral hepatitis, they cannot identify the specific virus, which is why antibody testing may be prescribed to confirm the underlying cause.

When should I get hepatitis A testing?

Doctors often recommend testing for hepatitis based on a patient’s medical history, symptoms, and physical exam.
Most adults with hepatitis A have symptoms that develop around 28 days after infection. Children under six years old rarely have symptoms. Symptoms of hepatitis A include:

• Dark urine
• Diarrhea and stool that is gray- or clay-colored
• Fatigue
• Low-grade fever
• Abdominal or joint pain
• Nausea, vomiting, or loss of appetite
• Yellow eyes and skin, also called jaundice

Doctors may recommend hepatitis A testing in patients with symptoms and a known exposure to HAV or an elevated risk of contracting this disease. Factors that increase the risk of exposure to hepatitis A include:

• Travel, especially to Asia, South America, Central America, Africa, and the Middle East
• Using intravenous drugs and the use of illegal drugs
• Living in a nursing home
• Working in industries involving health care, food, or sewage
• Eating raw shellfish, vegetables, and other foods

In patients who develop symptoms of hepatitis A without known exposure to the virus, doctors may recommend an acute viral hepatitis panel that looks for hepatitis A, hepatitis B, and hepatitis C in the same blood sample.