Irritable bowel syndrome and basal serum tryptase: correlation between subtype, severity, and comorbidities. A pilot study.

INTRODUCTION: the activation of mast cells causes alterations in epithelial and neuromuscular function and is involved in visceral hypersensitivity and dysmotility in gastrointestinal functional disorders. OBJECTIVES: primary: to evaluate differences in basal serum tryptase (BST) between patients with irritable bowel syndrome (IBS) and healthy controls. Secondary: BST depending on IBS subtype (diarrhea: IBS-D; constipation: IBS-C), comorbidities and correlation with IBS severity and quality of life. MATERIAL AND METHODS: a prospective control-case study in IBS patients (Rome IV criteria). BST (ImmunoCAP-Phadia, Sweden®), IBS Severity Score (IBSSS), pain, bloating and flatulence analogue scales, IBS quality of life (IBSQOL), and patient health status (PHQ-9) were determined. BST is the primary variable to achieve the primary endpoint. RESULTS: thirty-two patients were included, 21 (65.6 %) with IBS-D and 11 (34.4 %) with IBS-C; 32 controls were also included. Mean IBSSSS: 326.6 (± 71.4), IBSQOL: 76 (± 20.3), and PHQ9: 10.2 (± 5.9). BST was 4.8 ± 2.6 in IBS and 4.7 ± 2.6 in controls (p = 0.875). There were no differences in BST between IBS subtypes (4.7 ± 2.9 in IBS-D and 5 ± 1.8 in IBS-C; p = 0.315) or IBS severity (p = 0.662). However, BST was higher in patients with IBS and extraintestinal comorbidities compared to other patients and controls (p = 0.029). This subgroup also has more severe bloating (p = 0.021). There was no correlation between BST, quality of life (p = 0.9260), and health status (p = 0.3985). CONCLUSION: BST does not discriminate between IBS patients and controls. However, BST was higher in patients with IBS with extraintestinal comorbidities, which had more severe bloating. This finding is worthy of investigation.