Monospot test

Mononucleosis spot test

The mononucleosis spot test looks for 2 antibodies in the blood. These antibodies appear during or after an infection with the virus that causes mononucleosis, or mono.

How the Test is Performed
A blood sample is needed.


Why the Test is Performed
The mononucleosis spot test is done when symptoms of mononucleosis are present.


Common symptoms include:

Large spleen (possibly)
Sore throat
Tender lymph nodes along the back of the neck
This test looks for antibodies called heterophile antibodies. These form in the body during the infection.

Normal Results
A negative test means there were no heterophile antibodies detected. Most of the time this means you do not have infectious mononucleosis.

Sometimes, the test may be negative because it was done too soon (within 1 to 2 weeks) after the illness started. Your health care provider may repeat the test to make sure you do not have mono.

What Abnormal Results Mean
A positive test means heterophile antibodies are present. These are most often a sign of mononucleosis. Your provider will also consider other blood test results and your symptoms. A small number of people with mononucleosis may never have a positive test.

The highest number of antibodies occurs 2 to 5 weeks after mono begins. They may be present for up to 1 year.

In rare cases, the test is positive even though you do not have mono. This is called a false-positive result, and it may occur in people with:

Leukemia or lymphoma
Systemic lupus erythematosus

Alternative Names
Monospot test; Heterophile antibody test; Heterophile agglutination test; Paul-Bunnell test; Forssman antibody test