Lab

Monospot

search

Monospot, Mononucleosis Spot Test, Infectious Mononucleosis Slide Test, Heterophil Antibody Test, Heterophile Antibody Test, Heterophil Agglutination Tube Test, Paul-Bunnell Test, Mononucleosis Heterophile Test, Heterophile Antibodies

  • See Also
  1. Mononucleosis
  2. Mononucleosis-Like Syndrome
  3. Epstein-Barr Virus Antibody
  • Indications
  1. Infectious Mononucleosis suspected
  2. Mononucleosis-Like Syndrome
  • Mechanism
  1. Test for heterophile Antibody (Paul-Bunnell IgM)
    1. Not specific to EBV
    2. Uncommonly occurs in other conditions
  2. Heterophil Antibody agglutinates Red Blood Cells
    1. Horse RBCs (most sensitive) - used for slide test
    2. Bovine RBCs
    3. Sheep RBCs (least sensitive)
  1. False Negative Monospot common early in course
    1. Week 1: 25% False Negative Rate
    2. Week 2: 5-10% False Negative Rate
    3. Week 3: 5% False Negative Rate
  2. Positive Heterophile Antibody Tests
    1. Monospot positive at week 1 in 25% of patients
      1. Heterophile Antibodies are typically formed by 1 week of symptom onset
      2. But typically titers are too low for detection at this time
    2. Monospot positive by week 3 in >90% of patients
    3. Antibodies peak between weeks 2 and 5
  3. Heterophile Antibodies usually persist for 3 months
    1. Rarely antibodies persist up to 1 year
  4. Heterophile Antibody development is age specific
    1. Age under 2 years: <30% develop antibodies
    2. Age 2-4 years: <75% develop antibodies
    3. Age <12 years: <50% develop antibodies
    4. Age >12 years: >70% develop antibodies
    5. Adults >85% develop antibodies
  • Interpretation
  • Positive Test (>1:40 titer)
  1. Infectious Mononucleosis (Epstein-Barr Virus)
    1. See Mononucleosis for approach to testing
  2. False Positive causes (uncommon)
    1. Laboratory error (most common cause)
    2. CMV-Induced Mononucleosis
    3. Acute Retroviral Syndrome (Acute HIV Infection)
    4. Rubella
    5. Leukemia or Lymphoma
    6. Viral Hepatitis
    7. Influenza
    8. Varicella Zoster Virus
    9. Systemic Lupus Erythematosus
    10. Malaria
    11. Pancreatic Cancer
  • References
  1. Gantz in Noble (2001) Primary Care, Mosby, p. 268
  2. Ravel (1995) Lab Medicine, Mosby-Year, p. 263-4