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Mononucleosis Tests

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 .

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.

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 titres.

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 testfootnote 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 against EBV 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) but less than 1:320 usually means that you have been infected with EBV at some time in the past.

A titer of 1:320 or greater means that you have an active EBV infection (mononucleosis).

IgM against EBV is present.

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.
  • Having a weakened immune system.

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 necessarily mean that you have had a recent infection with EBV.
  • Although some people think that the Epstein-Barr virus (EBV) may be related to myalgic encephalomyelitis/chronic fatigue syndrome (ME/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

  1. 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 (2013). Laboratory Tests and Diagnostic Procedures, 6th 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

Current as of:
September 23, 2020

Author: Healthwise Staff
Medical Review:
E. Gregory Thompson MD - Internal Medicine
Anne C. Poinier MD - Internal Medicine
Adam Husney MD - Family Medicine
W. David Colby IV MSc, MD, FRCPC - Infectious Disease
Caroline S. Rhoads MD - Internal Medicine