Clinical validity of a continuous colorimetric method for serum lipase

Abstract

The clinical validity of a continuous colorimetric method for measuring pancreatic lipase was assessed. 1,2-Diacylglycerol containing long-chain fatty acid residues was used as substrate, and the method was adapted to a discrete analyser. The dynamic range was ascertained up to at least 30-fold the upper reference limit. Precision tests on three control sera yielded overall CVs of 4.6% (mean value 21 U/l), 2.4% (115 U/l), and 1.0% (386 U/l), respectively. Using serum samples from normal subjects and patients with pancreatic and non-pancreatic disorders, the present method was compared with a turbidimetric method (r = 0.997; n = 281) and a homogeneous enzyme immunoassay (r = 0.987; n = 93). The reference interval established on 121 healthy subjects was 8-57 U/l (central 95th percentile, median 22 U/l). The sensitivity of this lipase assay in the diagnosis of acute pancreatitis (100%, median 5.6-fold the upper reference limit) was equal to that of the pancreatic isoamylase assay, and higher than that of the total alpha-amylase assay (88.2%); the specificity for acute pancreatitis with respect to a group of patients with acute and chronic non-pancreatic abdominal diseases (91%) was higher than that of both pancreatic isoamylase (76%) and total alpha-amylase (71%).