Fecal pyruvate kinase: A potential new marker for intestinal inflammation in children with inflammatory bowel disease

Objective. Inflammatory bowel disease (IBD) in children creates diagnostic and clinical challenges. Clinical data, endoscopic appearance and the histopathological assessment of biopsies are essential for diagnosis. However, new methods are required for non-invasive follow-up. Recently, we demonstrated that the dimeric isoform of pyruvate kinase (PK) detected in stool might serve as a potential non-invasive screening tool in inflamed pouch mucosa. The aim of this study was to investigate whether this test could be used to detect intestinal inflammation in pediatric IBD patients. Material and methods. Fecal PK immunoreactivity was assessed in 75 patients with proven ulcerative colitis (UC) and 32 with Crohn's disease (CD). Pediatric Crohn Disease Activity Index (PCDAI) and Truelove-Witts scores were determined in CD and UC patients, respectively. Thirty-five healthy subjects (HS) served as a control group. Results. Increased PK levels were documented in 94.1% and 100% active CD patients with a cut-off level of 5 U/g and a cut-off level of 4 U/g, respectively, and in 94.3% of active UC patients regardless of cut-off level. Enzyme immunoreactivity was significantly higher in all IBD patients than in HS. Abnormal PK results were documented in 71.7% of all IBD patients (65.3% and 84.4 for UC and CD patients, respectively). Enzyme levels in UC remission were significantly lower than in the active phase. Enzyme immunoreactivity significantly correlated to both scoring systems. Conclusions. The measurement of stool PK could be a potentially useful marker of IBD activity in children. However, its clinical value demands further studies for comparison with other tests.