Tehran University of Medical Sciences Acta Medica Iranica 0044-6025 59 4 2021 05 18 197 202 Roberto Catanzaro Department of Clinical and Experimental Medicine, Gastroenterology Section, Gaspare Rodolico Hospital, University of Catania, Catania, Italy Alfio Maugeri Maugeri Department of Clinical and Experimental Medicine, Gastroenterology Section, Gaspare Rodolico Hospital, University of Catania, Catania, Italy Morena Sciuto Department of Clinical and Experimental Medicine, Gastroenterology Section, Gaspare Rodolico Hospital, University of Catania, Catania, Italy Fang He Department of Nutrition, West China School of Public Health, Sichuan University, Sichuan, China Baskar Balakrishnan Department of Immunology, Mayo Clinic, Rochester, MN, USA Francesco Marotta ReGenera R and D International for Aging Intervention and San Babila Clinic, Milano, Italy 2020 07 03 2021 02 18 The gastrointestinal pathologies have increased over the last years. The clinical pictures of inflammatory and irritable bowel disease might overlap, leading to expensive and invasive tests. Our study aims to investigate fecal calprotectin as an effective tool for differential diagnosis of gastrointestinal disorders. Two hundred fifty-six patients with the diagnosis of the gastrointestinal disorder and subjected to colonoscopy were collected for the statistical analysis of fecal calprotectin. The differential diagnosis of intestinal inflammation or non-inflammation was performed according to the Receiver Operating Characteristic (ROC) curve that outlines the Area Under Curve (AUC), Sensitivity (Se), Specificity (Sp). Fecal calprotectin was significantly elevated in patients with inflammatory bowel disease compared with patients with irritable bowel syndrome. Especially, the mean values of fecal calprotectin were 522 mg/g (IQR=215-975) and 21 mg/g (IQR=14-34.5) in patients with and without inflammation, respectively (P<0.0001). AUC value of fecal calprotectin was 0.958 (Se=88.9%, Sp=91.1%, with a cut-off value of 50 mg/g) for differentiating between inflammatory bowel disease and irritable bowel syndrome. Fecal calprotectin seems to be a non-invasive and inexpensive biomarker useful for the purpose of a differential diagnosis between inflammatory bowel disease and irritable bowel syndrome. https://acta.tums.ac.ir/index.php/acta/article/view/8599