A blood sample is needed. For information on how this is done, see: Venipuncture
How to prepare for the test
No special preparation is necessary.
How the test will feel
When the needle is inserted to draw blood, you may feel moderate pain, or only a prick or stinging sensation. You may feel throbbing at the site of the needle stick for a few minutes after the blood is taken.
Why the test is performed
The mononucleosis spot test is done when symptoms of mononucleosis are present. Common symptoms include:
Large spleen (possibly)
Tender lymph nodes along the back of the neck
This test looks for antibodies that form in the body during the infection, called heterophile antibodies.
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.
A small number of people with mononucleosis may never have a positive test.
What abnormal results mean
A positive test means heterophile antibodies are present. These are most often a sign of mononucleosis. Your health care provider will also consider other blood test results and your symptoms.
Antibodies reach their peak levels in 2 to 5 weeks, and may be present for up to 1 year.
Rarely, the test may be positive even though you do not have mono. This is called a false-positive result and may occur in persons with:
Weber R. Pharyngitis. In: Bope ET, Kellerman RD, eds. Conn's Current Therapy 2012. 1st ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 1.
Linda J. Vorvick, MD, Medical Director and Director of Didactic Curriculum, MEDEX Northwest Division of Physician Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.