Test Overview
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.
Risks
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.
Results
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.
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.
Hepatitis A test| Negative: | No hepatitis A virus (HAV) antibodies are
found. |
|---|
| Positive: | 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. - IgM anti-HAV
antibodies are found if you have an active or a recent infection. IgM antibodies usually
show up in the blood as early as 2 weeks after you become infected with HAV,
when symptoms of hepatitis A are present, and last for a few months after
symptoms have gone away.
- Only IgG anti-HAV
antibodies are found if you have had an infection in the past or when you have
had the hepatitis A vaccine. This means that you are protected against the
infection.
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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.
For more information, 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. 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. For more
information, see the topics
Bilirubin,
Alkaline Phosphatase,
Alanine Aminotransferase (ALT), and
Aspartate Aminotransferase (AST).
- 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.
References
Other Works Consulted
- Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby.
Credits
| By | Healthwise Staff |
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| Primary Medical Reviewer | E. Gregory Thompson, MD - Internal Medicine |
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| Specialist Medical Reviewer | W. Thomas London, MD - Hepatology |
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| Last Revised | August 30, 2012 |
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