Proceeds from website advertising help sustain Lab Tests Online. AACC is a not-for-profit organization and does not endorse non-AACC products and services.

Mono Test

Print this article
Share this page:
Also known as: Mononucleosis Spot Test; Mononuclear Heterophile Test; Heterophile Antibody Test; Monospot
Formal name: Heterophile Antibody Titer

The Test Sample

What is being tested?

Infectious mononucleosis, commonly called mono, refers to an infection caused by the Epstein-Barr virus (EBV). This test detects proteins in the blood called heterophile antibodies that are produced by the immune system in response to an EBV infection.

Infectious mononucleosis is characterized by a particular set of symptoms that most often affects adolescents. People who have mono often have a fever, sore throat, swollen glands, and fatigue. Many will also have an enlarged spleen, and a few may have an enlarged liver. Symptoms of the infection usually arise about one month after the initial infection and may last for several weeks. The associated fatigue may last for several months. Mono is usually a self-limiting condition; the symptoms resolve without any specific treatment.

Epstein-Barr virus is very common. According to the Centers for Disease Control and Prevention (CDC), up to 95% of people in the United States will have been infected by EBV by the time they are 40 years old. The virus is present in the saliva of an infected person and can be spread from person to person through close contact such as kissing and through sharing utensils or cups.

Most of the time, EBV infection occurs in childhood and causes few or no symptoms; however, if first exposure to the virus occurs in adolescence, it can cause symptoms associated with infectious mononucleosis in about half of those infected. Mono can affect anyone at any age, but its prevalence is highest in populations of young people, such as students in high schools or colleges, or in the military.

About 70% to 80% of those with mono produce heterophile antibodies, and these can be detected with a rapid screening mono test. These proteins are not specific for EBV but, when found in adolescents in conjunction with mono symptoms, they can be used to help diagnose infectious mononucleosis. If a mono test is negative and suspicion it still high, then a test specific for EBV antibodies may be performed.

A complete blood count (CBC) and blood smear are usually also performed, as mono is also characterized by a high white blood cell (WBC) count and the presence of atypical white blood cells (usually reported as reactive lymphocytes) as seen on a blood smear.

How is the sample collected for testing?

A blood sample is drawn by needle from a vein in the arm.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.