Hepatitis A Virus Test
Hepatitis A virus (HAV) test is a blood test that looks for proteins ( antibodies ) made by the body in response to the virus that causes hepatitis A. These proteins will be present in your blood if you have a hepatitis A infection now or have had one in the past. It is important to identify the type of hepatitis virus causing the infection to prevent it from spreading and to start the proper treatment.
HAV infection is spread through food or water that has been contaminated by the feces (stool) of an infected person.
- IgM anti-HAV antibodies mean a recent infection with hepatitis A virus. IgM anti-HAV antibodies generally can be detected in the blood as early as 2 weeks after the initial HAV infection. These antibodies disappear from the blood 3 to 12 months after the infection.
- IgG anti-HAV antibodies mean that you have had a hepatitis A viral infection. About 8 to 12 weeks after the initial infection with hepatitis A virus, IgG anti-HAV antibodies appear and remain in the blood for lifelong protection (immunity) against HAV.
Hepatitis A vaccine is available to prevent an HAV infection. If you have had this vaccine and you have anti-HAV antibodies, this means the vaccination was effective.
Why It Is Done
Hepatitis virus testing is done to:
- Identify the type of hepatitis virus causing a hepatitis infection.
- Screen people (such as doctors, dentists, and nurses) who have an increased chance of getting or spreading hepatitis A.
- Screen potential blood donors and donor organs to prevent the spread of hepatitis A.
- Find out whether a person has antibodies after getting a hepatitis A vaccine. If you had this vaccine and you now have antibodies to the hepatitis A virus (anti-HAV antibodies) in your blood, this means the vaccination was effective (you are immune to hepatitis A).
- Find out if a hepatitis A infection is the cause of abnormal liver function tests.
How To Prepare
You do not need to do anything before you have this test.
Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form (What is a PDF document?) .
How It Is Done
The health professional taking a sample of your blood will:
- Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
- Clean the needle site with alcohol.
- Put the needle into the vein. More than one needle stick may be needed.
- Attach a tube to the needle to fill it with blood.
- Remove the band from your arm when enough blood is collected.
- Put a gauze pad or cotton ball over the needle site as the needle is removed.
- Put pressure on the site and then put on a bandage.
How It Feels
The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.
There is very little chance of a problem from having blood sample taken from a vein.
- You may get a small bruise at the site. You can lower the chance of bruising by keeping pressure on the site for several minutes.
- In rare cases, the vein may become swollen after the blood sample is taken. This problem is called phlebitis. A warm compress can be used several times a day to treat this.
- Ongoing bleeding can be a problem for people with bleeding disorders. Aspirin, warfarin (such as Coumadin), and other blood-thinning medicines can make bleeding more likely. If you have bleeding or clotting problems, or if you take blood-thinning medicine, tell your doctor before your blood sample is taken.
Negative results of hepatitis virus testing mean that no antibodies against the hepatitis virus were found. Positive results mean that hepatitis A antibodies were found. Results are usually available in 5 to 7 days.
No hepatitis A virus (HAV) antibodies are found.
Hepatitis A virus (HAV) antibodies are found. You may need more tests to find out if you have a present, active infection or a past, resolved infection.
What Affects the Test
Many conditions can change anti-HAV antibodies levels. Your doctor will talk with you about any abnormal results that may be related to your symptoms and medical history.
Your results may need to be rechecked if you are taking some herbs or other natural products.
What To Think About
- Hepatitis A can be prevented by vaccination. To learn more, see the topic Immunizations.
- You also may be able to prevent a hepatitis A infection even after you have been exposed to the virus if you get a hepatitis A vaccination or a dose of immunoglobulin . To learn more, see the topic Hepatitis A.
- Hepatitis antibodies can take weeks or months to develop, so your results may be negative even though you have the early stages of an infection ( false-negative ).
- Other tests that show how well the liver is working are usually done if your doctor thinks you may have hepatitis. These tests can include measuring levels of bilirubin, alkaline phosphatase, alanine aminotransferase, and aspartate aminotransferase.
- Many states require that some types of hepatitis infections be reported to the local health department. The health department can then send out a warning to other people who may have been infected with the hepatitis virus, such as those who ate food served by a person who has the infection.
- Hepatitis A virus does not cause long-term illness, so there is no need for follow-up testing once the infection goes away.
Other Works Consulted
- Pagana KD, Pagana TJ (2010). Mosby?s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby.
|E. Gregory Thompson, MD - Internal Medicine|
|W. Thomas London, MD - Hepatology|
|Last Revised||August 30, 2012|
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