Fecal chymotrypsin and elastase-1 determination on one single stool collected at random: diagnostic value for exocrine pancreatic status
Molinari, I.; Souare, K.; Lamireau, T.; Fayon, M.; Lemieux, C.; Cassaigne, A.√©; Montaudon, D.√®l.
Clinical Biochemistry 37(9): 758-763
The secretin-cholecystokinin test is the "gold standard" to evaluate exocrine pancreatic function. But this direct duodenal intubation test is invasive, particularly in children, time-consuming, and expensive. For several years, indirect noninvasive tests of pancreatic insufficiency have been developed, such as fecal chymotrypsin (FChT) and fecal elastase-1 (FEL-1) measurements. Generally, elastase-1 is truly admitted to be the most relevant test of exocrine pancreatic status. However, so far, no consensus for stool collection protocol exists. The aim of our study was to investigate the diagnostic advantage from measuring fecal proteases in stool samples collected for two or three consecutive days in comparison to one single stool sample collected at random. A total of 69 children were divided into group A (stool samples collected for three consecutive days) and group B (stool samples collected for two consecutive days). These two groups included pancreatic-sufficient patients (PS) and severe pancreatic-insufficient patients (PI). One single determination of fecal chymotrypsin activity and of fecal elastase-1 concentration was realized on each stool. The same relatively important intraindividual variability of fecal proteases was observed in group A and B (mean coefficients of variation (CVs) 36% vs. 40.2% for chymotrypsin, 22.2% vs. 26.8% for elastase-1). No significant PS or severe PI diagnostic discordance was observed between 1, 2, or 3 days of stool collections. Our study clearly shows that the determination of fecal proteases on one single stool collected at random is sufficient to evaluate pancreatic exocrine status for PS and severe PI.