Clinical Spectrum in a Cohort of Patients With High Fecal Calprotectin Levels

Introduction: Distinguishing between inflammatory bowel disease (IBD) and functional gastrointestinal disorders is a diagnostic challenge. The need for non-invasive biomarker as a diagnostic tool in the assessment of gastrointestinal symptoms is required. The objectives of current study were to determine the spectrum of clinical features in patients tested for fecal calprotectin presenting with high levels and to compare calprotectin levels among already diagnosed patients known to have IBD as per biopsy findings and documented on patients' file with newly presenting patients who were being investigated and did not have a diagnosis. Methods: This retrospective cross-sectional study was conducted in the Department of Pathology and Laboratory Medicine and Department of Medicine, Aga Khan University, Karachi, Pakistan from January 2017 to December 2019. Subjects tested for fecal calprotectin who had elevated fecal calprotectin levels (n = 150) were included in the current study. Each patient deposited a random stool sample in an airtight container for calprotectin analysis. Biochemical analysis of calprotectin was performed by enzyme-linked immunosorbent assay using epitope calprotectin test kit (Epitope Diagnostics, Italy) on ETI-Max 3000 immunoassay analyzer (DiaSorin, Italy). A structured history form was used for data collection. Results: One hundred and fifty patients were available for inclusion in the final analysis. Majority of the patients (n = 117, 78%) were adults (>18 years of age), and 52.7% (n = 79) were females. Median fecal calprotectin (IQR) was 317.3 μg/g (549.10 - 239.2 μg/g) in children (n = 33) and 305 μg/g (609.9 - 201.6 μg/g) in adults; the difference was statistically non-significant (p value > 0.05). On categorization according to disease, fecal calprotectin levels were significantly elevated (p value = 0.033) in IBD patients compared to normal subjects, 644 μg/g (644 - 587.8 μg/g) vs 308.5 μg/g (505.4 - 233.8 μg/g), respectively. Diarrhea (n = 13, 38.4%), abdominal cramps (n = 12, 36.4%), and weight loss (n = 11, 33.3%) were the most common complaints noted in children with high fecal calprotectin levels, whereas in adults, abdominal cramps (n = 60, 51.3%), diarrhea (n = 59, 50.4%), and weight loss (n = 46, 39.3%) were the common complaints. The median fecal calprotectin levels in children already known to have IBD (n = 3) were higher than the levels noted in children with no diagnosis (n = 30); p value > 0.05. Similarly, median fecal calprotectin levels in adults with IBD (n = 28) were higher than the levels noted in patients with no specific diagnosis (n = 91), 400.7 μg/g (656.6 - 244.3 μg/g) vs 302.7 μg/g (564.6 - 206 μg/g); p value > 0.05. Conclusion: Current study affirms that the fecal calprotectin test can be used in identifying IBD patients in all age groups.