IgM, IgM anti-HAV
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. Most hepatitis infections are caused by 1 of 5 viruses: hepatitis A, B, C, D, or E. Because the symptoms of all of these infections are similar, this blood test can tell your healthcare provider 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. The average time to get symptoms after you are infected is 30 days. IgM antibodies usually begin to appear in your blood 5 to 10 days before you start having symptoms and can stay in your blood for about 6 months after the infection.
You can get 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.
You may need this test if your healthcare provider suspects you may have a liver infection caused by HAV. Your provider 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
Having sex with someone infected with HAV
Being a man who has sex with men
Working at a healthcare or daycare center
Sharing needles for IV (intravenous) drug use
Symptoms of HAV usually start suddenly and may include:
Yellow color of skin, eyes, and urine (jaundice)
Some people, especially children, may have HAV without symptoms.
Your healthcare provider may also check for antibodies to other types of hepatitis viruses. You may need other blood tests to check how your liver is working. Other tests for HAV are available, but the HAV antibody test is considered to be the most accurate.
Test results may vary depending on your age, gender, health history, the method used for the test, and other things. Your test results may not mean you have a problem. Ask your healthcare provider what your test results mean for you.
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:
You have an active HAV infection
You have had an HAV infection within the last 6 months
The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand.
Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore.
No other factors can affect your results.
You don't need to prepare for this test. Be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.