Simplified determination of intestinal protein excretion based on alpha 1-antitrypsin clearance.

Intestinal alpha 1-antitrypsin clearance in 6 healthy controls and 21 patients with Crohn's disease was measured simultaneously by two different methods. Faecal alpha 1-antitrypsin loss, determined conventionally by weight and alpha 1-antitrypsin concentration of the homogenized three day stool was compared with the faecal alpha 1-antitrypsin loss, which was calculated from weight of the three day stool sample and the mean alpha 1-antitrypsin concentration determined in three 1 g aliquots of the morning stool obtained at the three consecutive days during the collecting period. There was a significant correlation when comparing faecal alpha 1-antitrypsin loss (y = 0.96x + 10; r = 0.952) and intestinal alpha 1-antitrypsin clearance (y = 1.05x - 6.5; r = 0.974) measured by the different methods. Filling the aliquots by a standardized spoon into a vial prepared with a defined volume of solvent makes it possible to take a diluted, homogenized, and centrifuged stool sample out of the vial by the laboratory staff avoiding open faecal work up. The simplified method of measuring intestinal alpha 1-antitrypsin clearance permits to integrate the determination of enteric protein loss into routine diagnostics comparable to the faecal occult blood method.