Comparison of fecal pyruvate kinase isoform M2 and calprotectin in assessment of pediatric inflammatory bowel disease severity and activity.

AIMS Accurate assessment of inflammatory bowel disease (IBD) activity is the cornerstone of effective therapy. Fecal M2 isoform of pyruvate kinase (M2-PK) and fecal calprotectin (FC) are noninvasive markers of mucosal inflammation in IBD. The aim of this study was to compare performance of M2-PK and FC in assessment of pediatric ulcerative colitis (UC) and Crohn's disease (CD) severity and activity. MATERIALS AND METHODS 121 patients with IBD, including 75 with UC and 46 with CD were recruited. Control group consisted of 35 healthy children (HS). Patients were assigned to groups depending on disease severity and activity. M2-PK and calprotectin concentration were determined in stool samples using ELISA. Areas under receiver operating characteristic curves (AUC) for FC and M2-PK with cut-off level at which M2-PK specificity was matching FC specificity were calculated and compared. RESULTS Performance of M2-PK at identifying patients with IBD, UC and CD among HS was inferior to FC. The differences in AUC were respectively: -0.10 (95% confidence interval [CI] [-0.13-(-0.06)], p<0.0001), -0.14 (95% CI [-0.19-(-0.09)], p<0.0001) and -0.03 (95% CI [-0.05-(-0.001)], p<0.02). M2-PK was inferior to FC in discriminating patients with mild UC from those with HS (AUC difference -0.23, 95% CI [-0.31-(-0.15)], p<0.0001). CONCLUSIONS FC reflects pediatric IBD severity and activity better than M2-PK. This difference is particularly pronounced when identifying patients with mild UC and UC in remission.