Test Overview
Hepatitis B virus (HBV) tests check for
substances in the blood that show whether a
hepatitis B infection is active or has occurred in the
past. The tests look for different signs of infection (markers):
- Antigens are markers made by bacteria or viruses. So
the presence of HBV antigens means that the virus is in the
body.
- Antibodies are proteins produced by the
body to fight infection. The presence of HBV antibodies means that you have
been exposed to the hepatitis B virus at some time. But you could have been
infected long ago and gotten better, or you may have a current
infection.
- Genetic material (DNA) of the
hepatitis B virus shows that the virus is in the body. The amount of DNA can
help determine how severe the infection is and how easily the HBV infection can
be spread.
It is important to identify the type of hepatitis virus
causing infection to prevent its spread and choose the proper treatment.
Hepatitis B virus (HBV) testing
HBV is
transmitted through infected body fluids, including blood,
semen, and vaginal fluids (including menstrual blood).
It also can be transmitted from a pregnant woman to her child at or near the
time of birth.
There are several different HBV tests. These are
the HBV tests most commonly done:
- Hepatitis B surface antigen (HBsAg) is
the earliest sign of an active hepatitis B infection. This antigen may be
present before symptoms of an HBV infection are present. If this antigen is present for more than 6 months, then you probably have a chronic (long-term)
HBV infection. This means you can spread HBV to others throughout your
life.
- Hepatitis B surface antibody (HBsAb)
usually appears about 4 weeks after HBsAg disappears. The presence of this
antibody means that the infection is at the end of its active stage and you
cannot pass the virus to others (you are no longer contagious). This antibody
also protects you from getting HBV again in the future. The test is done to
determine the need for vaccination—the antibody will be present after receiving
the HBV vaccine series, showing that you have protection (immunity) from the
virus. Occasionally your test may show that you have both the HBsAb antibodies and HBsAg
antigen. In this case you are still contagious.
- Hepatitis B e-antigen (HBeAg) is an HBV protein that is only
present during an active HBV infection. This test determines how contagious you
are. Testing for this antigen can also be used to monitor the effectiveness of
treatment for HBV.
- HBV DNA testing checks
for genetic material (DNA) from the hepatitis B virus. The
HBV DNA tests measure how much genetic material is present. A high level of HBV
DNA means that the virus is multiplying in your body and you are very
contagious. If you have a chronic HBV infection, an elevated viral DNA level means you
are at an increased risk for liver damage and may want to consider treatment
with antiviral medicine. Testing for HBV DNA is also used to check the
effectiveness of treatment for long-term (chronic) HBV infection. HBV DNA testing is a more
sensitive test than HBeAg (above) for detecting HBV in the blood.
Other HBV tests are not done as often:
- Hepatitis B core antibody (HBcAb) is
an antibody to the hepatitis B core antigen that appears about 1 month after the start of an
active HBV infection. It can be found in people who had an infection in the
past and in those with long-term (chronic) HBV. It usually is present for life.
Blood banks test for this antibody when screening donated blood for hepatitis
B.
- Hepatitis B core antibody IgM (HBcAbIgM)
is another antibody to the hepatitis B core antigen. It indicates an HBV
infection that has occurred within the last 6 months. It can also mean that a chronic hepatitis B infection has flared up again.
- Hepatitis B e-antibody (HBeAb) shows that the active stage of
an acute HBV infection is almost over, and your risk of being contagious is
greatly reduced.
A hepatitis B vaccine is available to prevent an HBV
infection.
Hepatitis D virus (HDV) testing
Infection with the
hepatitis D virus (HDV), or delta agent, occurs only in
people who are already infected with the hepatitis B virus (HBV). Vaccination
against hepatitis B will prevent hepatitis D infection. Hepatitis D infection
is rare in the United States and Canada, except among people who inject illegal
drugs and those who are frequently exposed to blood products. The hepatitis D
test detects HDV antibodies. A positive test indicates only that you have been
infected with HDV—it cannot distinguish between an acute or chronic infection.
Another test, the HDV RNA test, is needed to determine whether you have an
active HDV infection. It does not distinguish between an acute or chronic
infection. This test currently is not available except in research
settings.
Since hepatitis B infections can be spread through
sexual contact, practice safer sex until your test results are returned.
Why It Is Done
Hepatitis B virus testing is done
to:
- Identify the type of hepatitis B virus
infection. Testing can determine whether an infection has occurred recently or
in the past. Other tests that show how well the liver is functioning are
usually done to help make treatment decisions.
- Screen people who
have a higher risk of getting or spreading a hepatitis B infection, such as
doctors, dentists, and nurses.
- Screen blood donors and donor organs
to prevent the spread of hepatitis B.
- Find out if a person has
developed antibodies after receiving vaccinations for hepatitis B. The presence
of antibodies to hepatitis B virus (HBsAb) means that the vaccinations were
effective.
- Find out if abnormal liver function tests are being
caused by hepatitis B.
- Monitor how well treatment of chronic
hepatitis B is working.
How To Prepare
No special preparation is needed
before having hepatitis virus testing.
Talk to your doctor about any concerns you have regarding the need for the test, its
risks, or how it will be done. 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 drawing 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.
- Apply a gauze pad or cotton ball over the needle site as
the needle is removed.
- Apply pressure to the site and then a
bandage.
How It Feels
You may feel nothing at all from the
needle puncture, or you may feel a brief sting or pinch as the needle goes
through the skin. Some people feel a stinging pain while the needle is in the
vein. But many people do not feel any pain (or have only minor discomfort)
after the needle is positioned in the vein. The amount of pain you feel depends
on the skill of the health professional drawing the blood, the condition of
your veins, and your sensitivity to pain.
Risks
Blood test
There is very little risk of
complications from having blood drawn from a vein.
- You may develop a small bruise at the
puncture site. You can reduce the risk of bruising by keeping pressure on the
site for several minutes after the needle is withdrawn.
- In rare
cases, the vein may become inflamed after the blood sample is taken. This
condition is called phlebitis and is usually treated with a warm compress
applied several times a day.
- Continued bleeding can be a problem
for people with bleeding disorders. Aspirin, warfarin (Coumadin), and other
blood-thinning medicines can also make bleeding more likely. If you have
bleeding or clotting problems, or if you take blood-thinning medicine, tell
your health professional before your blood is drawn.
Results
Hepatitis B
virus tests check for substances in the blood that show a
hepatitis infection is active or has occurred in the
past. The tests look for
antigens or genetic material (DNA) of the
virus that causes hepatitis. Some tests also look for
antibodies that the body makes against the virus.
Normal results of hepatitis virus testing are called negative. This means that
no antigens, antibodies, or genetic material related to the hepatitis B virus
was found.
Abnormal (positive)
Hepatitis B and D virus testsHepatitis B (HBV) | Hepatitis B (HBV) antibodies and/or
antigens are detected. More tests may be needed to determine whether you
have an acute or chronic (long-term) HBV infection. - Hepatitis B surface antigen (HBsAg) shows an active infection. If the test remains positive
for longer than 6 months, this means you have a chronic HBV infection. You can spread
the HBV infection to others.
- Hepatitis B surface antibody (HBsAb) shows the end of active infection and means you are
protected against HBV for life. It also can show that you received the HBV
vaccine. Occasionally the test shows that you have both HBsAb antibodies and the HBsAg
antigen. In this case you are still contagious.
- Hepatitis B e-antigen (HBeAg) shows an active contagious
state.
- HBV DNA testing finds genetic
material (DNA) from the hepatitis B virus and means that you have a current
infection.
- Hepatitis B core antibody (HBcAb)
shows that you have been infected with HBV. It does not tell the difference
between a past or present infection.
- Hepatitis B core antibody IgM (HBcAbIgM) shows an HBV infection that has occurred
within the last 6 months. It can also mean that a chronic hepatitis B infection has flared up.
- Hepatitis B e-antibody (HBeAb) shows a less active HBV infection. You are less contagious but
can still infect others.
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Hepatitis D (HDV) | Hepatitis D antibodies are found. But this
test cannot tell the difference between an acute and a chronic infection.
Hepatitis D can only be present if hepatitis B is present. |
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What Affects the Test
Your doctor will talk with you
about anything that may stop you from having the test or that may change the
test results.
What To Think About
- Hepatitis B can be prevented by vaccination.
The presence of
antibodies to the hepatitis B virus may mean that
you have developed immunity to the infection after being vaccinated. The
hepatitis B vaccination protects against hepatitis D infection
also.
- Hepatitis antibodies can take weeks or months to develop, so
a person infected with hepatitis may initially test negative if testing is done
early in the infection.
- People who have received the hepatitis B
vaccine can have HBsAb antibodies without having any of the other hepatitis B
markers (HBcAb, HBeAb, HBsAg, HBeAg, and HBV
DNA).
- All
donated blood and organs are tested for hepatitis before being
used.
- Other tests that show how well the liver is working are
usually done along with hepatitis B tests. Examples include measurement 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).
- In many
states, some types of hepatitis infections must be reported to the local health
department. The health department can then issue a warning to other people who
may have been infected with the hepatitis virus, such as those who are close
contacts of someone with hepatitis B.
References
Other Works Consulted
- Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis:
Saunders.
- Fischbach FT, Dunning MB III, eds. (2009).
Manual of Laboratory and Diagnostic Tests, 8th ed.
Philadelphia: Lippincott Williams and Wilkins.
- 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 | Kathleen Romito, MD - Family Medicine |
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| Specialist Medical Reviewer | W. Thomas London, MD - Hepatology |
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| Last Revised | October 29, 2012 |
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