Usefulness of a simple photometric determination of chymotrypsin activity in stools--results of a multicentre study.

The usefulness of a new photometric test for the determination of chymotrypsin activity in stools was evaluated in a multicentre study. By release of the enzyme from stool particles with a cationic detergent solution after, in most cases, 3 min of homogenization, a photometric measurement of the enzyme activity is possible both in the clear supernatant after centrifugation and in the diluted stool homogenate. The precision of the activity measurement in stool samples with pathologically lowered and normal chymotrypsin activity is good both for in-series (CV = 2.6%, scatter 0.6-5.7%) and for day-to-day determinations (CV = 7.2%, scatter 3.9-13.9%). The results obtained by the photometric determination also exhibit a close correlation with the values measured by pH-stat titrimetry (r = 0.901). The sample-preparation system with a sample-metering chamber is easy to use and gives good agreement with determinations in which the sample metering was done by weighing out the stool (r = 0.961). The photometric test for detection of exocrine pancreatic insufficiency is easy to perform, inexpensive and does not place any undue stress on the patient.