[Determination of the ribonuclease activity of the duodenal contents of children as a test in the differential diagnosis of cystic fibrosis and pancreatic exocrine insufficiency].

Ribonuclease activity was determined in the duodenal contents of healthy children, in children with cystic fibrosis and with pancreatic exocrine insufficiency. Assays were made at 7.0, in 0.05 M buffer without and with 0.35 M NaCl. The ratio of activity in 0.35 M NaCl to that in buffer alone was found to be 2.4 +/- 1.3 for children with cystic fibrosis as compared with 12 +/- 5 for the control group and children with pancreatic exocrine insufficiency.