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 131 I-polyvinylpyrrolidone (PVP), 95 Nb-albumin, 59 Fe dextran, 67 CU ceruloplasmin or 51 Cr-labeled serum proteins. A complete analysis of protein metabolism may be achieved through the simultaneous use of 51 Cr-iabeled proteins and 125 I-labeled proteins. The size of the protein pools and rates of protein synthesis and catabolism can be determined from analysis of the 25 I-protein data and the rate of protein loss into the gastrointestinal tract quantitated ith clearance; studies using 51 Cr-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.