Fluorometric serum lipase assay: evaluation of monodecanoyl fluorescein as substrate

The elements of the mechanized fluorometric lipase (EC 3.1.1.3) assay of Fleisher and Schwartz [Clin. Chem. 17, 417 (1971)] were made optimum; a manual adaptation was also developed. Hydrolysis of the monodecanoyl fluorescein substrate by hog pancreatic lipase is a zero-order reaction. The hydrolytic activity of normal human serum, serum from hospitalized patients without pancreatitis, and serum from patients with acute pancreatitis showed considerable overlap. Bile salts, considered activators in titrimetric or turbidimetric lipase assays, inhibited hydrolysis of the substrate by human serum. We conclude that monodecanoyl fluorescein is not a specific substrate for the serum lipase measured in acute pancreatitis.