The fate of 131 I-labelled human pancreatic elastase after intraduodenal administration.

Human pancreatic elastase labelled with 131 I was administered into the duodenum through the fiberoptic gastro-duodenoscope in eight persons. Radioactivity was measured in their plasma, urine and feces during 72 h. 131 I was present in the plasma in a dialyzable form 15 min after administration in all but one person. In one case labelled elastase bound by alpha1-antitrypsin and alpha2-macroglobulin was recovered from plasma indicating absorption of elastase from the intestine. In all individuals most of the radioactivity (28 - 73%) was recovered in the urine. Their feces contained low amounts of labelled substance (0.9 - 7.0%), except in two individuals where large amounts of radioactivity were found in the feces of one person with diarrhoea (43%) and of another, who received oral treatment with antibiotics two months previously (22%). In the latter case endogenous elastase was also present in feces in considerable amounts.