Els van de Vijver

39 INTRODUCTION Inflammatory bowel diseases (IBD), including Crohn’s disease and ulcerative colitis, are lifelong conditions that often begin in childhood. Suspicion is raised in children and teenagers with chronic abdominal pain and diarrhoea. Additional red flag symptoms including rectal bleeding, weight loss, and anaemia increase the suspicion of the condition. Endoscopic evaluation of the upper and lower gastrointestinal tract with biopsies for histology is essential to diagnose IBD and to differentiate Crohn’s disease from ulcerative colitis and IBD- unclassified, start appropriate therapy and prevent progressive bowel damage.(1) Many children consider endoscopy and the required bowel preparation to be uncomfortable.(2) Identification of children with a low likelihood of IBD would justify a non-invasive “watchful waiting” strategy, while on the other hand identification of those with a sufficiently high likelihood of IBD would justify urgent referral to specialist services for endoscopy. In recent years the stool calprotectin test has been promoted as a safe and easy interpretable triage tool for endoscopy.(3,4) Calprotectin is mainly released by neutrophil granulocytes, but other cells including monocytes and epithelial cells do also excrete this protein.(5) To date, a calprotectin concentration below 50 µg/g has been proposed to rule out IBD and not to proceed to endoscopy.(6,7) However, there are concerns about the mediocre specificity of the test at this threshold, which may give rise to a considerable proportion of children and teenagers proceeding to a pointless invasive procedure. Calgranulin-C (S100A12) is a less frequently investigated marker of intestinal inflammation that is almost exclusively released by activated granulocytes.(5) In previous case-control studies calgranulin-C showed diagnostic promise with better specificity compared to calprotectin,(8-10) but large studies in a prospective cohort with chronic abdominal pain and diarrhoea are lacking. The aim of this study was to compare calprotectin and calgranulin-C to see which of the two markers best predicted IBD in children and teenagers with chronic abdominal pain and diarrhoea. Head-to-head comparison Calgranulin C and Calprotectin 39