II. Indications
III. Mechanism
- Test for heterophile Antibody (Paul-Bunnell IgM)
- Not specific to EBV
- Uncommonly occurs in other conditions
- Heterophil Antibody agglutinates Red Blood Cells
- Horse RBCs (most sensitive) - used for slide test
- Bovine RBCs
- Sheep RBCs (least sensitive)
IV. Timing: Positive for Mononucleosis
-
False Negative Monospot common early in course
- Week 1: 25% False Negative Rate
- Week 2: 5-10% False Negative Rate
- Week 3: 5% False Negative Rate
- Positive Heterophile Antibody Tests
- Monospot positive at week 1 in 25% of patients
- Heterophile Antibodies are typically formed by 1 week of symptom onset
- But typically titers are too low for detection at this time
- Monospot positive by week 3 in >90% of patients
- Antibodies peak between weeks 2 and 5
- Monospot positive at week 1 in 25% of patients
- Heterophile Antibodies usually persist for 3 months
- Rarely antibodies persist up to 1 year
- Heterophile Antibody development is age specific
- Age under 2 years: <30% develop antibodies
- Age 2-4 years: <75% develop antibodies
- Age <12 years: <50% develop antibodies
- Age >12 years: >70% develop antibodies
- Adults >85% develop antibodies
V. Interpretation: Positive Test (>1:40 titer)
-
Infectious Mononucleosis (Epstein-Barr Virus)
- See Mononucleosis for approach to testing
- False Positive causes (uncommon)
VI. References
- Gantz in Noble (2001) Primary Care, Mosby, p. 268
- Ravel (1995) Lab Medicine, Mosby-Year, p. 263-4