Test Catalog

Test ID: MONOS    
Infectious Mononucleosis, Rapid Test, Serum

Useful For Suggests clinical disorders or settings where the test may be helpful

Rapid confirmation of a diagnosis of infectious mononucleosis

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Infectious mononucleosis (IM) is a viral illness that involves reticuloendothelial tissue and is generally limited to children and young adults. IM is most commonly caused by Epstein-Barr virus (EBV). The disease is characterized by fever, sore throat, lymphadenopathy, headache, and fatigue and, on a symptomatic basis, may be confused with other diseases.


Detectable levels of unique heterophile antibodies are produced in patients with IM.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.


Reference values apply to all ages.

Interpretation Provides information to assist in interpretation of the test results

Detectable levels of the infectious mononucleosis (IM) heterophile antibody can usually be expected to occur between the sixth and tenth day following the onset of symptoms. The level usually increases through the second or third week of illness and, thereafter, can be expected to persist, gradually declining over a 12-month period.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Approximately 10% of patients with infectious mononucleosis (IM) will have no heterophile antibody and may require Epstein-Barr virus (EBV) antibody tests to confirm the diagnosis.


False-negative results have been reported. Some of these may represent cases of IM that remain persistently seronegative for the IM heterophile antibody. However, some false-negative results have been shown to be due to a delayed IM heterophile antibody response.


IM heterophile antibody titers have been shown to persist in some cases for months and years after clinical symptoms have subsided. Conversely, IM heterophile antibodies have been detected prior to the onset of clinical symptoms. Thus, caution should be exercised in the interpretation of test results.


The IM heterophile antibody has been associated with several diseases other than IM. These include leukemia, Burkitt' lymphoma, pancreatic carcinoma, viral hepatitis, cytomegalovirus infections, and others. In these cases, it is difficult to disprove the possibility of concurrent disease states.


Some segments of the population do not produce detectable heterophile antibodies, eg, approximately 50% of children under 4 years of age and 10% of adolescents.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Davidsohn I, Walker PH: The nature of heterophilic antibodies in infectious mononucleosis. Am J Clin Pathol. 1935;5:445-465

2. Peter J, Ray CG: Infectious mononucleosis. Pediatr Rev. 1998;19(8):276-279

3. Johannsen EC, Kaye KM: Epstein-Barr virus (infectious mononucleosis, Epstein-Barr virus-associated malignant diseases, and other diseases). In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Elsevier; 2020:1872-1890