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Beaumont Laboratory

Monospot (Heterophile Assay)

Infectious Mononucleosis, EPIC: LAB5839, SOFT: MONO

Specimen Collection Criteria

Collect (preferred specimen): One Gold-top SST tube. (Minimum Whole Blood: 4.0 mL)
Also acceptable: One Lavender-top EDTA tube. (Minimum Whole Blood: 3.0 mL) 

Physician Office/Drawsite Specimen Preparation

Let serum specimens clot 30-60 minutes. Centrifuge to separate serum or plasma from cells. Transfer serum or plasma to a plastic transport tube and refrigerate (2-8°C or 36-46°F).

Preparation for Courier Transport

Transport: Centrifuged collection tube or plasma specimen, refrigerated (2-8°C or 36-46°F). (Min: 0.5 mL)

Rejection Criteria

  • Hemolyzed specimens.
  • Severely lipemic specimens.
  • Specimens with gross bacterial contamination.


Specimen Stability for Testing:

Centrifuged SST Tubes and Microtainers® with Separator Gel
Room Temperature (20-26°C or 68-78.8°F): 24 hours
Refrigerated (2-8°C or 36-46°F): 24 hours
Frozen (-20°C/-4°F or below): Unacceptable

Red-top Tubes, Lavender-top Tubes, and Microtainers® without Separator Gel
Room Temperature (20-26°C or 68-78.8°F): 24 hours
Refrigerated (2-8°C or 36-46°F): 24 hours
Frozen (-20°C/-4°F or below): Unacceptable

Serum Specimens (Pour-Overs)
Room Temperature (20-26°C or 68-78.8°F): 24 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 3 months

Plasma Specimens (Aliquots)
Room Temperature (20-26°C or 68-78.8°F): 24 hours
Refrigerated (2-8°C or 36-46°F): 24 hours
Frozen (-20°C/-4°F or below): 24 hours

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days


Farmington Hills Transfusion Medicine Laboratory (Blood Bank).
Grosse Pointe Microbiology Laboratory.
Royal Oak Special Testing Laboratory.
Troy Hematology/Coagulation Laboratory.


Sunday - Saturday, 24 hours a day.
STAT results available within 60 minutes.
Routine results available within 24 hours.

Reference Range

Reported as positive or negative.

Test Methodology

Latex Agglutination.


Assay results should be interpreted in regards to the patient's clinical symptoms.

Heterophile antibodies are usually detectable at the onset of symptoms and reach peak levels within 2 weeks. Heterophile antibody levels decline rapidly thereafter and are usually not detectable after 3 months. Heterophile tests are not suitable for testing sera from children under 12 years of age because they do not always produce heterophile antibodies during primary EBV infection. (1)

False-negative results may occur if the specimen is collected before detectable levels of heterophile antibodies have developed. A repeat assay is indicated for patients if their symptoms persist.

Clinical Utility

This assay is used as an aid in the diagnosis of infectious mononucleosis (IM).

Clinical Disease

Adolescents and adults who escape EBV infection during childhood experience infectious mononucleosis (IM) upon primary infection with EBV. IM is characterized by irregular fever, pharyngitis, and lymphadenopathy lasting 1 to 4 weeks. Hematological abnormalities include an absolute increase in lymphocytes and monocytes exceeding 50% and more than 15% atypical lymphocytes, lasting for at least 2 weeks. Liver function tests generally reveal a mild to moderate increase in SPGT, SGOT, bilirubin, and LDH levels. IM is usually a benign and self- limited disease. Complications including splenomegaly and splenic rupture, hepatitis, pericarditis, myocarditis, or central nervous system involvement (Guillain-Barre syndrome, Bell's palsy, transverse myelitis, and meningoencephalitis) may occur following IM infection. (1)


Most cases occur sporadically. There is no seasonal variability.

Incubation Period

4-7 weeks.


IM is transmitted via salivary contact through kissing or exposure to contaminated eating utensils.


  1. Wiedbrauk D, Johnston SLG. Manual of Clinical Virology, Raven Press, New York, NY, 1993.

CPT Code


Test Codes


Last Updated


Microtainer® and Vacutainer® are registered trademarks of Becton, Dickinson and Company.
UroVysion® is a registered trademark of Abbott Laboratories. ThinPrep® is a registered trademark of Hologic, Incorporated.

This directory currently reflects information only for specimens collected and/or processed at the Farmington Hills, Grosse Pointe, Royal Oak, and Troy campuses.