Diagnostic value of fecal calprotectin in inflammatory bowel disease and irritable bowel syndrome and correlation with inflammation markers

Objective: Our study aimed to reveal the correlation of Fecal Calprotectin (FC) with inflammation markers (CRP, NLR (Neutrophil Lymphocyte Ratio), WBC, ESR (Erythrocyte Sedimentation Rate), Hemoglobin, Hematocrit, Platelet) and endoscopic activity index. It also aims to determine its role in the differential diagnosis of Inflammatory Bowel Disease (IBD) and Irritable Bowel Syndrome (IBS). It was aimed to investigate the correlation of fecal calprotectin with less invasive inflammation markers that are frequently used in clinical practice and to facilitate the diagnosis and follow-up of diseases. Materials and Methods: Patients who applied to Yeditepe University Hospital Gastroenterology Polyclinic between 2017-2023 with various complaints and who were asked for inflammation markers, fecal calprotectin tests and also underwent colonoscopy were included in the study. Patient files were reviewed retrospectively. Fecal calprotectin, CRP, NLR (Neutrophil Lymphocyte Ratio), WBC, ESR (Erythrocyte Sedimentation Rate), Hemoglobin, Hematocrit, Platelet values of a total of 97 patients were recorded on the date of colonoscopy. Patients were divided into two groups as IBS (46 patients) and IBD (51 patients). All patients included in the study with the diagnosis of IBD had active disease. Findings: In our study, the mean FC value was determined as 552 mcg/mg in patients followed up with a diagnosis of IBD, and the mean FC value was determined as 48 mcg/mg in patients followed up with a diagnosis of IBS, and this was found to be statistically significant (p<0.05). While no significant correlation was found between FC and CRP values in patients followed up with a diagnosis of IBD, a highly significant positive correlation (p=0.01) was found between FC and NLR. A significant correlation was found between FC and WBC, NEU values in our patients, but no significant correlation was found between FC and PLT, HB, SEDIM values. A significant correlation relationship was found between Endoscopic Activity Index (EAI) and FC in patients with a diagnosis of IBD (p=0.02). In ROC analysis, FC was found to have the highest sensitivity and specificity. Conclusion: There are several reasons why laboratory markers have been studied in IBD in recent years. First, since symptoms are subjective, the aim is to obtain an objective measure of disease activity and avoid invasive procedures such as endoscopy that burden the patient. The purpose of using the fecal calprotectin test in IBD is to have high specificity in the absence of intestinal infection and to provide easy access to stool. In our study, it was observed that FC has a very high sensitivity and specificity in differentiating IBD-IBS patients in our clinical practice. With the increase in its use in our clinical practice, it is aimed to reduce unnecessary endoscopic procedures in IBD-IBS patients and to alleviate the burden of these procedures on our healthcare system. Keywords: C-Reactive Protein, Fecal Calprotectin, Inflammatory Bowel Disease, Inflammatory Bowel Disease Activity Index, Neutrophil/Lymphocyte Ratio