A simplified colorimetric assay of pancreas-specific lipase in plasma as well as duodenal juice using α-naphthyl palmitate as substrate was developed for the clinical use.
The method described by Whitaker was revised by adding deproteinization step, using standardized Fast violet A and increasing alkaline amount in the color development. By sephadex G-200 column chromatography of plasma and duodenal samples, the lipase activity measured by the present method was approximately parallel to that determined by C14-triolein as substrate, which should express pancreas-specific lipase activity.
Lipoprotein lipase and trypsin did not show any activity by the described method. Only minor activity was noted for the commertial pseudocholine esterase and liver esterase. However, in hepatitis with marked elevation of plasma GOT or GP r, normal level of plasma lipase was observed, and no elevation of lipase activity was found in plasma with elevated pseudocholine esterase activity.
In acute pancreatitis, plasma lipase activity was elevated by 7-30 fold and the elevation seemed to be greater than that of amylase. In subjects with hyperamylasemia above 300 Somogyi U/dl, abnormally elevated lipase activity was found in 87% witti significant correlation (r=0.54) between the two enzyme activities.
These data indicate that the described method for lipase determination is simple and expresses pancreas-specific lipase activity in plasma as well as in duodenal samples. These determinations may be useful to evaluate and clinically follow the exocrine-pancreatic function.
