Test Overview
The hepatitis A virus test is a blood test that shows whether you have a hepatitis A infection.
The test looks for antibodies made by the body to fight the virus. They will be in your blood if you
have a hepatitis A infection now or have had one in the past.
- Hepatitis A IgM antibodies can be found as early as 2 weeks after you are first infected. They disappear 3 to 12 months after
the infection.
- Hepatitis A IgG antibodies appear 8 to 12 weeks after you are first infected. They stay in your blood and protect you from hepatitis A permanently.
Why It Is Done
Hepatitis virus testing is done
to:
- Identify the type of hepatitis virus causing the infection.
- Screen people who have a higher chance of getting or spreading hepatitis
A. This includes doctors, dentists, and nurses.
- Screen blood donors and donor organs. This is done to help prevent the
spread of hepatitis A.
- Find out if a person has antibodies
after getting a hepatitis A vaccination. Having antibodies means the vaccine worked.
- Find out if hepatitis A is the cause of abnormal
liver function tests.
How To Prepare
You don't need to do anything special to prepare for this test.
Talk to your doctor if you have any concerns about 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.
Risks
There is very little chance of a problem from
having a blood sample taken.
- 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. You can use a warm compress several times a day to treat this.
Results
The hepatitis A virus test is a blood test that shows whether you have a hepatitis A infection.
The test looks for antibodies made by the body to fight the virus. They will be in your blood if you
have a hepatitis A infection now or have had one in the past.
Hepatitis A test| Negative: | No hepatitis A virus antibodies are
found. |
|---|
| Positive: | Hepatitis A antibodies are found.
You may need more tests to find out if you have a present, active infection or
a past infection that got better. - IgM antibodies
are found if you have an active or a recent infection. These antibodies usually
show up as early as 2 weeks after you become infected. They last for a few months after
symptoms have gone away.
- IgG antibodies
are found if you had an infection in the past or have
been vaccinated.
|
|---|
What Affects the Test
Your doctor will talk with you
about anything that might keep you from having the test or that may change the
test results.
Your results may need to be checked again 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 they might not show up in a test done early in the infection.
- Tests that show how
well your liver is working are usually done if your doctor thinks you may have
hepatitis. These tests may include measuring bilirubin, alkaline
phosphatase, alanine aminotransferase, and aspartate aminotransferase.
- In many states, some types of hepatitis infections must be reported to the local
health department. The health department can then send out a warning to others who may have been infected. This may include people who
ate food served by a person who has the infection.
- Hepatitis A
virus does not cause long-term illness. There is no need for follow-up
testing after the infection goes away.
References
Other Works Consulted
- Pagana KD, Pagana TJ (2010). Mosby's Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby.
Credits
ByHealthwise Staff
Primary Medical ReviewerE. Gregory Thompson, MD - Internal Medicine
Adam Husney, MD - Family Medicine
Specialist Medical ReviewerW. Thomas London, MD - Hepatology
Current as ofMarch 3, 2017