Test Overview
Mononucleosis tests are blood tests to look
for
antibodies that indicate
mononucleosis (mono), which is usually caused by the
Epstein-Barr virus (EBV). The antibodies are made by
the
immune system to fight an infection.
Mono
tests include:
-
Monospot test (heterophil test). This quick
screening test detects a type of antibody (heterophil antibody) that forms
during certain infections. A sample of blood is placed on a microscope slide
and mixed with other substances. If heterophil antibodies are present, the
blood clumps (agglutinates). This result usually indicates a mono infection.
Monospot testing can usually detect antibodies 2 to 9 weeks after a person is
infected. It typically is not used to diagnose mono that started more than 6
months earlier.
-
EBV antibody test. For this test, a sample of blood
is mixed with a substance that attaches to antibodies against EBV. A series of
tests can detect different types of antibodies to help determine whether you
were infected recently or sometime in the past.
Why It Is Done
The
monospot test is done to help diagnose a recent
mono infection.
Epstein-Barr virus (EBV)
antibody testing is
also done to help diagnose mono. The EBV antibody test can help determine
whether you have ever been infected with the virus and whether the infection
has been recent.
EBV antibody testing is usually done when you
have symptoms of infectious mononucleosis and a monospot test result is
negative. EBV antibody testing may also be done to check for
antibodies to EBV when a person has a disease or uses
medicine that causes problems with the
immune system.
How To Prepare
No special preparation is required
before having 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 monospot test is done on a small
sample of blood taken from your fingertip or from a vein. The Epstein-Barr
antibody test is done on a blood sample taken from your vein.
Blood test from a finger stick
For a fingertip
sample, the health professional taking the sample will:
- Clean your hand with soap and warm water or
an alcohol swab.
- Massage your hand without touching the puncture
site.
- Puncture the skin on the side of your middle or ring finger
with a small instrument called a lancet.
- Wipe away the first drop
of blood.
- Place a small tube called a capillary tube on the
puncture site and collect a small amount of blood.
- Put a gauze pad
or cotton ball over the puncture site as the tube is removed.
- Put
pressure on the site and then put on a bandage.
Blood test from a vein
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 or from your fingertip. You may feel nothing at all from the needle or
lancet, or you may feel a quick sting or pinch. The elastic band that is
wrapped around your upper arm when blood is taken from a vein may feel
tight.
Risks
There is very little chance of a problem from
having a blood sample taken from your fingertip or 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 who have bleeding disorders. Aspirin, warfarin (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
Mononucleosis tests are blood tests to
look for
antibodies that indicate mononucleosis (mono), which is usually caused by the
Epstein-Barr virus (EBV). The antibodies are made by
the
immune system to fight an infection.
Monospot test
The results of a monospot test are
usually ready within 1 hour.
Monospot test
| Normal
(negative): |
The blood sample does not
form clumps (no heterophil
antibodies are detected).
|
| Abnormal
(positive): |
The blood sample clumps
(heterophil antibodies are detected). If the blood sample clumps, you probably
have mono.
|
Epstein-Barr antibody testing
The results of the
antibody test to detect
Epstein-Barr virus (EBV) may be reported as
positive (antibodies are present) or negative (antibodies are not present). Or the test results may be reported in
titers. A titer is a measure of how much the blood
sample can be diluted before the antibodies against the Epstein-Barr virus
(EBV) can no longer be detected.
The EBV antibody test can also detect the type of antibodies
(immunoglobulins) present in the blood. The type of antibody shows whether
the infection is recent or old. The antibody IgM is only found during the
active phase of mono. The antibody IgG can be found later, when you are
starting to get better.
The results of an EBV antibody test are
usually ready within 3 days.
EBV antibody test
1
| Normal
(negative): |
The titer is less than 1 to
10 (1:10). A titer of less than
1:10 means that you have never been exposed to EBV.
No IgM
is present. If IgG is present, it may mean that you have been exposed to EBV in
the past.
|
| Abnormal
(positive): |
A titer greater than 1 to
10 (1:10) usually means that you have
been infected with EBV at some time.
A titer of 1:320 or greater means that you have an
active EBV infection (mononucleosis).
IgM is
present. IgG may also be present but may mean that you have been exposed to EBV
in the past.
|
What Affects the Test
Reasons you may not be able to
have the test or why the results may not be helpful include:
- Having an EBV antibody test within the first
few weeks of becoming infected with EBV. This may lead to a
false-negative result. If the first test does not
indicate mono but you still have symptoms, the test may be repeated.
- Other infection or disease, such as
cytomegalovirus (CMV),
leukemia or
lymphoma,
rubella,
hepatitis, or
lupus. Although the symptoms of these infections and
diseases are similar to mono, the monospot test usually will be
negative.
What To Think About
- Since many people are exposed to Epstein-Barr
virus (EBV) during childhood, most adults have EBV
antibodies of a type called IgG. The presence of the
IgG type of antibody does not mean that you have had a recent infection with
EBV.
- Rapid diagnostic tests for mono are not useful for children
younger than 4 years.
- Although some people think that the
Epstein-Barr virus (EBV) may be related to
chronic fatigue syndrome (CFS), experts have found no
evidence for this. The monospot test and the EBV antibody test are not used to
diagnose or monitor CFS.
- Children, especially those younger than 2 years, are more likely
than adults to have a negative monospot test, even when they have mono. This is
called a
false-negative result.
References
Citations
-
Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.
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 Elsevier.
Credits
|
By
|
Healthwise Staff |
|
Primary Medical Reviewer
|
E. Gregory Thompson, MD - Internal Medicine |
|
Specialist Medical Reviewer
|
W. David Colby IV, MSc, MD, FRCPC - Infectious Disease |
|
Last Revised
|
October 3, 2012 |