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; howev er, very few patients with malabsorption due to small intestine diseases ha ve been included in the previous studies. The aim of the study was to compa re the diagnostic accuracy of fecal EL-1 and fecal chymotrypsin (FCT) in di stinguishing between pancreatic maldigestion and intestinal malabsorption. Three groups of subjects were studied: group A included 49 patients with kn own cystic fibrosis (25 males, median age 5 years); group B included 43 sub jects with various small intestine diseases (17 males, median age 6 years); and group C included 45 children without any history of gastrointestinal d isease (22 males, median age 5 years). In all patients, stools were collect ed for 72 h on a standard diet and fecal EL-1, FCT, and steatocrit tests we re performed. Both EL-1 and FCT were below normal limits in all CF patients with pancreatic maldigestion not treated with pancreatic enzyme (100% sens itivity for both assays); El-1, but not FCT, was also below normal in all t he CF patients with pancreatic maldigestion treated with pancreatic extract s. Both EL-1 and FCT values in the CF group were significantly lower than i n subjects with various small intestinal diseases and in children without a ny history of gastrointestinal disease (P < 0.0001). FCT, but not EL-1, val ues 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 histor y of gastrointestinal disease; in contrast, specificity was 86% for EL-1 an d 76% for FCT if we considered the control group with small intestinal dise ases: low EL-1 was observed in two cases of intestinal giardiasis, two case s of short bowel syndrome, one case of celiac disease, and one case of inte stinal pseudobstruction; FCT was abnormal in four cases of intestinal giard iasis, three cases of celiac disease, one case of short bowel syndrome, one case of Crohn's disease, and one case of intestinal pseudobstruction. Diag nostic accuracy was 92% for fecal EL-1 and 82% for FCT. Steatocrit values w ere 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 belo w the normal limit. In conclusions, in patients with CF, fecal EL-1 determi nation is not more sensitive than FCT in identifying pancreatic maldigestio n; however, fecal EL-1 assay is more specific than FCT determination in dis tinguishing pancreatic maldigestion from intestinal malabsorption.