Reference values of fecal calgranulin C (S100A12) in school aged children and adolescents

Background: Calgranulin C (S100A12) is an emerging marker of inflammation. It is exclusively released by activated neutrophils which makes this marker potentially more specific for inflammatory bowel disease (IBD) compared to established stool markers including calprotectin and lactoferrin. We aimed to establish a reference value for S100A12 in healthy children and investigated whether S100A12 levels can discriminate children with IBD from healthy controls. Methods: In a prospective community-based reference interval study we collected 122 stool samples from healthy children aged 5-19 years. Additionally, feces samples of 41 children with suspected IBD (who were later confirmed by endoscopy to have IBD) were collected. Levels of S100A12 were measured with a sandwich enzyme-linked immunosorbent assay (ELISA) (Inflamark (R)). The limit of detection was 0.22 mu g/g. Results: The upper reference limit in healthy children was 0.75 mu g/g (90% confidence interval: 0.30-1.40). Median S100A12 levels were significantly higher in patients with IBD (8.00 mu g/g [interquartile range (IQR) 2.5-11.6] compared to healthy controls [0.22 mu g/g (IQR <0.22); p <0.001]). The best cutoff point based on receiver operating characteristic curve was 0.33 mu g/g (sensitivity 93%; specificity 97%). Conclusions: Children and teenagers with newly diagnosed IBD have significantly higher S100A12 results compared to healthy individuals. We demonstrate that fecal S100A12 shows diagnostic promise under ideal testing conditions. Future studies need to address whether S100A12 can discriminate children with IBD from nonorganic disease in a prospective cohort with chronic gastrointestinal complaints, and how S100A12 performs in comparison with established stool markers