INTESTINAL CLEARANCE OF ALPHA-1-ANTITRYPSIN - A SENSITIVE METHOD FOR THE DETECTION OF PROTEIN-LOSING ENTEROPATHY

Abstract

Gastrointestinal loss of plasma is usually measured with radiolabeled macromolecules. These methods are expensive and cumbersome. The use of .alpha.1-antitrypsin as an endogenous marker and the determination of .alpha.1-antitrypsin fecal clearance enable the diagnosis of protein-losing enteropathy [in patients]. .alpha.1-Antitrypsin is measured in feces and blood by radial immunodiffusion and the results are expressed as clearance. There is a significant correlation between .alpha.1-antitrypsin fecal clearance and 51Cr-plasma protein clearance (r = 0.96, P < 0.001). The sensibility of .alpha.1-antitrypsin test compared to [51Cr] is 93.3%, the specificity is 90%. The positive predictive value is 97.7%, the negative predictive value 75%. No .alpha.1-antitrypsin was found in gastric juice of pH below 3. In vitro studies confirmed the destruction of .alpha.1-antitrypsin in gastric juice of pH below 3. There is a slight decrease of .alpha.1-antitrypsin concentration when stools are incubated at 37.degree. C. In duodenal juice there is a small lessening of .alpha.1-antitrypsin concentration after an incubation at 37.degree. C for 1 h. The fecal clearance of .alpha.1-antitrypsin is apparently an inexpensive and quite reliable test of protein-losing enteropathy.