Differential determination of serum isoamylase using an amylase inhibitor and its clinical application

Diagnostic significance of a simple and rapid screening procedure for determining the relative amounts of pancreatic and salivary isoamylase using an amylase inhibitor was evaluated in 242 subjects (controls 84, acute pancreatitis nine, chronic pancreatitis 28, pancreatic cancer 14, peptic ulcer 25, liver cirrhosis 15, cholelithiasis 24, irritable colon syndrome 13, diabetes mellitus 13, mumps seven, and chronic renal failure 10). Electrophoretically separated isoamylases of saliva and pure pancreatic juice were all inhibited at similar degrees to the corresponding unfractionated amylases. Total amylase and pancreatic isoamylase were elevated in all nine patients with acute pancreatitis. Pancreatic isoamylase was decreased in 12 of 28 patients (43%) with chronic pancreatitis and increased in nine of 14 patients (64%) with pancreatic cancer. The mean pancreatic isoamylase activity in the patients with acute pancreatitis was significantly higher (p less than 0.01), while that of chronic pancreatitis was significantly lower (p less than 0.05) when compared with controls. The inhibition method offers simple, rapid, and specific analysis of serum isoamylase for the differential diagnosis of hyperamylasemia in cases of emergency.