This study was performed in 1952 at Case Western Reserve University. During the two decades prior to the study, several studies of protein digestion and absorption were carried out both in normal individuals and in patients with various diseases. This study describes a simple and accurate method to determine the efficiency of protein digestion and absorption, by measuring the isotope content of the feces after oral ingestion of protein labeled with iodine-131 (I131). The subjects were 10 children with diseases that did not specifically involve the gastrointestinal tract and 5 children with cystic fibrosis of the pancreas. These patients fasted for 12 hours before the experiment; then, a test meal containing I131 was orally administered in place of breakfast. The test meal contained approximately 1 microcurie of labeled protein per kilogram of body weight. In the five children with cystic fibrosis of the pancreas, pancreatin was withheld for 3 days prior to and during the initial test. The subjects ranged in age from 1.6 years to 9 years. The research demonstrated a diminished retention of dietary protein in cystic fibrosis of the pancreas. This research was supported by a U.S. Atomic Energy Commission contract.
Lavik, P.S., L.W. Matthews, G.W. Buckaloo, S. Spector, and H.L. Friedell. Use of I131 Labeled Protein in the Study of Protein Digestion and Absorption in Children with and without Cystic Fibrosis of the Pancreas. Cleveland: Western Reserve University, NYO 4025, August 15, 1952.