Hepatitis A blood tests check for immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies. An IgG-positive and IgM-negative result may suggest immunity to hepatitis A.
A doctor may request a hepatitis A test for IgG, IgM, or both. The results can show whether a person has a hepatitis A infection currently or has had one in the past. They can also indicate whether the individual could benefit from vaccination.
Read on to learn more about hepatitis A testing, including what the results mean. This article will also explain how doctors treat the hepatitis A virus.
If a doctor suspects a person has hepatitis A, they may request a blood test. They may also use this test before or after a person has a hepatitis A vaccine.
During a hepatitis A blood test, a healthcare professional takes a sample of a person’s blood. They then send this sample to a laboratory for testing.
Hepatitis A tests check a person’s blood for IgG, IgM, or both.
IgM antibodies
The immune system produces IgM antibodies when a person first experiences exposure to the hepatitis A virus.
A positive IgM result may indicate that a person currently has hepatitis A or has had a hepatitis A infection in the last 6 months.
IgG antibodies
A person’s immune system produces IgG antibodies after IgM antibodies.
They increase in number over several months and are generally present in the body for the rest of a person’s life. IgG antibodies help prevent a person from contracting the hepatitis A virus again.
If a person has a positive IgG result, it may indicate that they have had a previous hepatitis A infection or that they have received a hepatitis A vaccination.
An IgG-positive and IgM-negative result
An IgG-positive and IgM-negative result may suggest a person is immune to hepatitis A. This can occur if they have previously experienced a hepatitis A infection. Immunity can also occur following vaccination.
Other results
The following table from the
| Total hepatitis A virus antibody test (both IgG and IgM) result | IgM only test result | Meaning |
|---|---|---|
| Positive | Positive | A person is currently carrying the hepatitis A virus, has recently carried it, or has received a hepatitis A vaccination recently. |
| Positive | Not performed | A person is currently carrying the hepatitis A virus or has recently carried it. |
| Positive | Negative | There is evidence of prior exposure to the hepatitis A virus, either through infection or vaccination, but no evidence suggestive of current or recent infection. |
| Negative | Negative | There is no evidence that a person’s immune system has experienced exposure to the hepatitis A virus. The person may be susceptible to infection. |
| Negative or not performed | Positive | There is evidence suggestive of current or recent exposure to the hepatitis A virus, such as with ongoing infection. Alternatively, the result may be a false positive. |
Hepatitis A is an infectious condition of the liver.
A person can contract it from close contact with someone who is carrying the hepatitis A virus. They can also contract it by consuming food or drinks that contain the virus.
The
- nausea
- vomiting
- fatigue
- fever
- abdominal pain
- loss of appetite
- diarrhea
- pale or clay-colored stools
- dark urine
- joint pain
- jaundice, which is the yellowing of the skin and whites of the eyes
The
A person’s doctor
- rest
- drinking plenty of fluids
- adequate nutrition
A healthcare professional may also recommend that a person avoid medications that can affect the liver, such as acetaminophen.
If a person has severe symptoms of hepatitis A, such as liver failure, they may require hospitalization.
Below are answers to some of the most common questions about hepatitis A IgG and IgM.
What is the difference between hepatitis A IgM and IgG?
Hepatitis A IgM and IgG are two types of antibodies.
When a person first contracts an infection, the body produces IgM antibodies. These help provide short-term protection while the immune system creates other antibodies.
IgG antibodies help the body protect itself from further infections. Hepatitis A IgG antibodies help prevent a person from catching hepatitis A in the future.
How long does hepatitis A IgG stay positive?
Once a person has a positive hepatitis IgG result, their blood is typically hepatitis IgG-positive for the rest of their life.
What does “IgM not detected” mean in hepatitis A?
If a hepatitis A IgM test does not detect any IgM antibodies, this is a negative result. This can mean there are no IgM antibodies in a person’s bloodstream or the amount of IgM in the blood is too low for the test to detect.
A negative hepatitis A IgM result may mean a person does not currently have hepatitis A. Further testing may indicate if a person has immunity to hepatitis A or if they could benefit from vaccination.
Hepatitis A is a liver infection caused by the hepatitis A virus. A doctor can perform blood tests to determine whether a person carries or has carried this virus.
Doctors use hepatitis A blood tests to check a person’s blood for hepatitis A IgM and IgG antibodies. The presence of these antibodies can show whether a person has a hepatitis A infection currently or has had one in the past. They can also indicate whether the individual could benefit from a hepatitis A vaccine.
A hepatitis A IgG-positive and IgM-negative test result means a person has carried the virus or received a hepatitis A vaccination. This means they may have immunity to the virus.
People should contact a doctor if they experience any symptoms of hepatitis A, such as dark urine, pale or clay-colored stools, and jaundice.