Protein-losing enteropathy and kinetic studies of plasma protein metabolism

Abstract

Protein-losing enteropathy is a common phenomenon associated with over 85 diseases affecting the gastrointestinal tract. Such loss may be secondary to disorders of gastrointestinal lymphatic channels, ulceration of the gastrointestinal mucosa, or mechanisms as yet undefined. Excessive gastrointestinal protein loss may be diagnosed by determining the fecal excretion of label following the intravenous administration of labeled macromolecules that are not normally secreted or absorbed from the gastrointestinal tract such as 131I-polyvinylpyrrolidone (PVP), 95Nb-albumin, 59Fe dextran, 67CU ceruloplasmin or 51Cr-labeled serum proteins. A complete analysis of protein metabolism may be achieved through the simultaneous use of 51Cr-iabeled proteins and 125I-labeled proteins. The size of the protein pools and rates of protein synthesis and catabolism can be determined from analysis of the 25I-protein data and the rate of protein loss into the gastrointestinal tract quantitated ith clearance; studies using 51Cr-serum proteins. In addition to their value in pinpointing the inestinal tract as diseased, the radionuclides used for quantitation of gas trointestinal protein loss have also been of value in determining the site of disease in the intestinal tract determining the activity of the gastrointestinal disease, and following the efficacy of therapy.of the intestinal disorder. Finally, such studies have led to the discovery of new clinical syndromes involving the gastrointestinal tract.