Hepatitis A Antibody
Does this test have other names?
IgM, IgM anti-HAV
What is this test?
This test looks for antibodies in your blood called IgM. The test can find out whether you are infected with the hepatitis A virus (HAV).
Hepatitis is an inflammation of your liver, often caused by an infection. About 95 percent of hepatitis infections are caused by one of five viruses: hepatitis A, B, C, D, or E. Because the symptoms of all of these infections are similar, this blood test can tell your doctor which type of virus you may have.
Your immune system makes IgM antibodies when you are first infected with HAV. It can take 14 to 50 days to develop symptoms of hepatitis A after you become infected. IgM antibodies usually begin to appear in your blood five to 10 days before you start having symptoms and can stay in your blood for about six months after the infection.
You can acquire HAV by eating or drinking a food or beverage contaminated with the virus. The virus is also in the bowel movements of infected people, so you could get infected by coming in contact with someone who has the infection. In rare cases, you can get the virus from a contaminated needle.
HAV infection usually clears up on its own within a few weeks or months. Once you have had HAV, you will probably never have it again. This is called having immunity to the infection.
Why do I need this test?
You may need this test if your doctor suspects you may have a liver infection caused by HAV. Your doctor may order this test if you have symptoms of HAV and you have a history that puts you at risk for being in contact with the virus. Risk factors for HAV include:
Traveling to a country with high rates of HAV infection
Having contact with or eating contaminated food
Being in close contact with a person who has HAV
Working at a health care or daycare center
Sharing needles for intravenous drug use
Symptoms of HAV usually start suddenly and may include:
Some people, especially children, may have HAV without symptoms.
What other tests might I have along with this test?
Your doctor may also check for antibodies to other types of hepatitis viruses. You may need other blood tests to check how your liver is working.
What do my test results mean?
Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.
Normal results are negative, meaning that you don't have the hepatitis A IgM in your blood.
If your test is positive or reactive, it may mean:
How is this test done?
The test requires a blood sample, which is drawn through a needle from a vein in your arm.
Does this test pose any risks?
Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.
What might affect my test results?
No other factors can affect your results.
How do I get ready for this test?
You don't need to prepare for this test.
- Alteri, Rick, MD
- Bass, Pat F. III, MD, MPH