Quantitative evaluation of serum pancreatic isoamylases in cystic fibrosis.

The amylase in sera of 20 patients with cystic fibrosis of the pancreas (CFP), 17 of whom had pancreatic insufficiency (PI), and of 34 normal control subjects was separated into its pancreatic and salivary components and quantitated. Electrophoretic separation was achieved on polyacrylamide disc gels with subsequent sectioning of the gel columns. The amylase content in international units per liter (IU/L.) was obtained for each section by the insoluble blue starch substrate method. The mean total serum amylase of the CFP patients with PI was significantly lower than the control group. A highly significant decrease was found when the pancreatic isoamylase was considered alone. The salivary isoamylase level remained essentially the same. Three patients with CFP but without PI demonstrated higher than normal pancreatic amylase values in the serum. These patients may be in an early stage of a progressive involvement of the pancreas in which there is an increased release of amylase. This method of electrophoretic separation and quantitation of the serum amylase is sensitive and efficient and allows the simultaneous processing of multiple specimens. The results obtained agree with previously published ratios of serum isoamylases. Our method should be valuable in the study of other diseases of the exocrine pancreas and salivary glands.