Fecal Calprotectin Levels in Children is more tightly Associated with Histological than with Macroscopic Endoscopy Findings

Background: Children with suspected bowel inflammation require an invasive endoscopic procedure, which is usually performed under general anesthesia. To improve the selection of candidates for endoscopy, fecal calprotectin level has been proposed as a noninvasive marker of intestinal inflammation. In the future, home testing is a likely option. Thus, the aim of this study was to affirm the association between bedside-measured fecal calprotectin concentration and histological and endoscopic findings in a panel of patients with suspected chronic bowel inflammation. Methods: Stool samples and microscopic and macroscopic findings from 41 patients, who underwent ileocolonoscopy for suspicion of bowel inflammation, were consecutively obtained between April 2009 and December 2010. Stool samples were analyzed using the bedside fecal calprotectin enzyme-linked immunosorbent assay (Quantum Blue; Buhlmann, Laboratories AG, Switzerland). Results: Fecal calprotectin levels were elevated in 18 children with bowel inflammation on endoscopy (median at the upper limit of undiluted samples, 300 mu g/g) compared with 23 children without bowel inflammation (median, 105 mu g/g; p < 0.00097). Similarly, the fecal calprotectin level was elevated in 25 children with positive histological findings as assessed by a pathologist (median, 300 mu g/g) compared with 16 children without histological inflammation (median, 73 mu g/g; p < 0.000014). Based on the optimal area under the curve, we calculated the cutoff fecal calprotectin level for bowel inflammation on endoscopy as 167 mu g/g (area under the curve, 0.86; 95% confidence interval (CI), 0.81 - 0.92) and on histological examination as 280 mu g/g (area under the curve, 0.78; 95% CI, 0.70 0.86). Fecal calprotectin level was more sensitive than endoscopy for diagnosis of microscopic bowel inflammation (p = 0.000014). Conclusions: Our results clearly show that even the bedside test for fecal calprotectin level, using the optimal cutoff value, is feasible enough in determining candidates for an endoscopic procedure in order to confirm bowel inflammation and is more tightly associated with histological findings than with endoscopic findings. Thus, the calprotectin level reflects histological activity, even in cases with normal endoscopic findings. The bedside test described herein is a sufficient screening method for this purpose.