This
refers to the outer surface of the hepatitis B virus that triggers an antibody
response. A "positive" or "reactive" HBsAg test result means
that the person is infected with the hepatitis B virus. This can be an "acute"
or a "chronic" infection. Infected people can pass the virus on to others
through their blood.
HBsAb
or anti-HBs (hepatitis B surface antibody)
This refers to the protective antibody that is produced in response to an infection.
It appears when a person has recovered from an acute infection and cleared the
virus (usually within six months) or responded successfully to the hepatitis B
vaccine shots. A "positive" or "reactive" HBsAb (or anti-HBs)
test result indicates that a person is "immune" to any future hepatitis
B infection and is no longer contagious. This test is not routinely included in
blood bank screenings.
HBcAb
or anti-HBc (hepatitis B core antibody)
This refers to an antibody that is produced in response to the core-antigen, a
component of the hepatitis B virus. However, this is not a protective antibody.
In fact, it is usually present in those chronically infected with hepatitis B.
A "positive" or "reactive" HBcAb (or anti-HBc) test result
indicates a past or present infection, but it could also be a false positive.
The interpretation of this test result depends on the first two test results.
Its appearance with the protective surface antibody (positive HBsAb or anti-HBs)
indicates prior infection and recovery. For chronically infected persons, it will
usually appear with the virus (positive HbsAg).
Is
there a blood test for hepatitis B?
There
is a simple hepatitis B blood test that your doctor or health clinic can order
called the hepatitis B blood panel. This blood sample can be taken
in the doctors office. There are 3 common tests that make up this blood
panel. Sometimes the doctor may ask to check your blood again six months after
your first visit to confirm your hepatitis B status. If you think you have been
recently infected with hepatitis B, it will take 4 -6 weeks before the virus will
be detected in your blood.
Understanding
your hepatitis B blood test results can be confusing, so you want to be clear
about your diagnosis - do you have a new infection, have you recovered from a
past infection, or do you have a chronic infection? In addition, it is helpful
if you request a written copy of your blood tests so that you fully understand
which tests are positive or negative.
What
three tests make up the "hepatitis B blood panel"?
The
hepatitis B blood panel requires only one blood sample but includes three tests:HBsAg
(hepatitis B surface antigen) HBsAb or Anti-HBs (hepatitis B surface
antibody) HBcAb or anti-HBc (hepatitis B core antibody)
The
doctor needs all 3 blood test results in order to determine your diagnosis.
What
is the hepatitis B surface antigen (HBsAg)? This
tests for the presence of virus. A "positive" or "reactive"
HBsAg test result means that the person is infected with the hepatitis B virus,
which can be an "acute" or a "chronic" infection. Infected
people can pass the virus on to others through their blood and infected bodily
fluids.
What
is the hepatitis B surface antibody (HBsAb or anti- HBs)?
A
"positive" or "reactive" HBsAb (or anti-HBs) test result indicates
that a person has successfully responded to the hepatitis B vaccine or has recovered
from an acute hepatitis B infection. This result means that you are immune to
future hepatitis B infection and you are not contagious. This test is not routinely
included in blood bank screenings.
What
is the hepatitis B core antibody (HBcAb)?
The
HBcAb is an antibody that is part of the virus- it does not provide protection.
A "positive" or "reactive" HBcAb (or anti-HBc) test result
indicates a past or present infection, but it could also be a false positive.
The interpretation of this test result depends on the results of the other two
tests. Its appearance with the protective surface antibody (positive HBsAb or
anti-HBs) indicates prior infection and recovery. For chronically infected persons,
it will usually appear with the virus (positive HBsAg).
I
donated blood and received a letter about hepatitis B from the blood bank, what
does it mean?
First,
do not panic. The letter does not necessarily mean that you are infected with
hepatitis B. All
donated blood is screened for hepatitis B. Many blood banks use the "hepatitis
B core antibody" test to screen donor blood for potential hepatitis B infection.
This test can detect whether a person might have been exposed to the hepatitis
B virus, but by itself this blood test doesn't tell whether the person is actually
infected or not. This is why it is very important to see your doctor so that he
can order the hepatitis B blood panel to make an accurate diagnosis.
Source: Centers
for Disease Control and Prevention
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