Tryptase: A New Measure (or Predictor) of the Extent of GI Involvement in Eosinophilic Esophagitis (EoE)?

Abstract

Purpose: Several investigators have noticed increased levels of tryptase positive mast cells in the esophagi of patients with EoE. Serum tryptase is elevated in patients suffering from anaphylaxis and mastocytosis, but has not been reported in EoE patients. Since elevations in tryptase levels have been shown to be predictive of the severity of allergic reactions, we measured baseline tryptase levels in a cohort of patients with EoE and observed whether elevated levels correlated with disease extent and severity. Methods: Retrospective study involving 46 patients (27 male, 19 female) diagnosed with eosinophillic esophagitis on the basis of biopsy. Additionally, 8 patients in this cohort were eventually found to have eosinophils on gastric and small bowel biopsies. The tryptase levels (ImmunoCap; Phadia) were available for review in 42 of the patients. Univariate analysis was performed to compare tryptase levels with associated symptoms and findings on chart review. Results: 8 out of 42 patients (19%) had elevated tryptase levels (> 10.4 serum value). The mean tryptase level was 7.7±4.42. The mean peripheral blood eosinophil count was 481±295. On univariate analysis, 5 of the 8 (63%) of those with elevated tryptase had evidence of eosinophilic gastroenteritis as compared to 6 out of 34 (11%) with normal tryptase levels (p=0.02). The mean tryptase level for patients with eosinophilic gastroenteritis was 10.3 with a standard deviation of 6.5. There were no differences in reported seasonal or food allergies between those with elevated tryptase as compared to normal tryptase values (p=NS). There were significant differences in reported abdominal pain in patients with elevated tryptase levels (p=0.01). However, no differences in cramping (38% versus 12%) or loose stools (63% versus 26%) occurred in patients with elevated versus normal tryptase. In those with elevated tryptase, resolution of eosinophilic gastroenteritis correlated with normalization of the serum tryptase. Conclusion: The role of tryptase in patients with EoE and food allergies is not completely understood but significant elevations in serum tryptase may indicate more diffuse disease such as eosinophilic gastroenteritis. Patients with elevated levels also appeared to have more abdominal pain. Gastric and small bowel biopsies should be performed in EoE patients with elevated serum tryptase as such testing may reveal more diffuse involvement of gastrointestinal eosinophilia and tryptase levels may serve as a non invasive marker to assess response to therapy.