Diagnostic accuracy of fecal elastase 1 assay in patients with pancreatic maldigestion or intestinal malabsorption: a collaborative study of the Italian Society of Pediatric Gastroenterology and Hepatology.

Several reports have indicated that fecal elastase-1 (EL-1) determination is a new, sensitive, and specific noninvasive pancreatic function test; however, very few patients with malabsorption due to small intestine diseases have been included in the previous studies. The aim of the study was to compare the diagnostic accuracy of fecal EL-1 and fecal chymotrypsin (FCT) in distinguishing between pancreatic maldigestion and intestinal malabsorption. Three groups of subjects were studied: group A included 49 patients with known cystic fibrosis (25 males, median age 5 years); group B included 43 subjects with various small intestine diseases (17 males, median age 6 years); and group C included 45 children without any history of gastrointestinal disease (22 males, median age 5 years). In all patients, stools were collected for 72 h on a standard diet and fecal EL-1, FCT, and steatocrit tests were performed. Both EL-1 and FCT were below normal limits in all CF patients with pancreatic maldigestion not treated with pancreatic enzyme (100% sensitivity for both assays); El-1, but not FCT, was also below normal in all the CF patients with pancreatic maldigestion treated with pancreatic extracts. Both EL-1 and FCT values in the CF group were significantly lower than in subjects with various small intestinal diseases and in children without any history of gastrointestinal disease (P < 0.0001). FCT, but not EL-1, values showed an inverse statistically significant correlation with steatocrit values in the whole CF group (P < 0.001); FCT was below normal in three of four CF patients with steatorrhea on pancreatic enzyme therapy. Both EL-1 and FCT had 100% specificity when calculated in children without any history of gastrointestinal disease; in contrast, specificity was 86% for EL-1 and 76% for FCT if we considered the control group with small intestinal diseases: low EL-1 was observed in two cases of intestinal giardiasis, two cases of short bowel syndrome, one case of celiac disease, and one case of intestinal pseudobstruction; FCT was abnormal in four cases of intestinal giardiasis, three cases of celiac disease, one case of short bowel syndrome, one case of Crohn's disease, and one case of intestinal pseudobstruction. Diagnostic accuracy was 92% for fecal EL-1 and 82% for FCT. Steatocrit values were over the normal limit in 11 patients with small intestine diseases; in 7/11 of these patients at least one of the pancreatic test results was below the normal limit. In conclusions, in patients with CF, fecal EL-1 determination is not more sensitive than FCT in identifying pancreatic maldigestion; however, fecal EL-1 assay is more specific than FCT determination in distinguishing pancreatic maldigestion from intestinal malabsorption.