Hepatitis B Virus Tests
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
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
- 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
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
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
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.