Background: The diagnosis of inhalant allergies involves a medical history, physical exam, and allergen sensitivity testing; allergen sensitivity can be assessed by a specific immunoglobulin E (IgE) screen for inhalant allergens. Some patients with clinical suspicion for inhalant allergies have a negative specific IgE screen, but high total IgE. We theorize that elevated total IgE may indicate a false-negative screen caused by "missed allergens" not initially identified.
Methods: Study patients with a negative allergy screen and elevated IgE (>116 kU/L) were identified (n = 26). Control patients (n = 26) were defined as having a negative screen and an IgE <2.95 kU/L. Both groups were tested with an expanded specific IgE panel and completed a questionnaire about other causes of elevated IgE.
Results: The expanded panel was positive for inhalant allergens in 4 study patients (15%) and 0 control patients (p = 0.037). Within the study patients, 50% had asthma and 76.9% had chronic sinusitis. Only 2 control patients had asthma (11.5%), p = 0.003; 4 (19.2%) reported chronic sinusitis, p < 0.0001. Food allergen sensitivity was identified in 5 study patients and 1 control, p = 0.083.
Conclusion: This pilot study evaluated patients clinically suspected of allergy with a negative inhalant IgE screen. Those with a high total IgE were more likely to have a missed inhalant allergen on expanded testing, as well as asthma and chronic sinusitis, compared to those with a low total IgE. Further investigation of "missed antigen" and the role of chronic respiratory inflammatory disease in patients with elevated total IgE is warranted.
Keywords: allergic rhinitis; asthma; immunoglobulin E; radioallergosorbent test; respiratory hypersensitivity; sinusitis.
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