The purpose of this study was to determine if routine
isoamylase assay would provide valuable diagnostic information in patients with
hyperamylasemia.
Isoamylase distribution was determined in sera of 37 consecutive hyperamylasemic patients. The attending physicians (without knowledge of the
isoamylase level) had considered
acute pancreatitis to be "probable" in 19, "possible" in 4, and "unlikely" in 14 of these 37 patients. Three of the patients considered probably to have
pancreatitis and 3 thought possibly to have
pancreatitis had normal serum pancreatic
isoamylase levels. Knowledge of the normal pancreatic
isoamylase level in these 6 patients probably would have changed the clinical diagnosis to some condition other than
pancreatitis. Of the 14 hyperamylasemic patients thought "unlikely" to have
pancreatitis, 7 had an elevation of just pancreatic
isoamylase and 3 additional patients had elevation of both pancreatic and salivary isoamylases. It seems likely that knowledge of these elevated pancreatic
isoamylase levels would have changed the clinical diagnosis to "probable"
pancreatitis for many of these patients. We conclude that routine
isoamylase assay provides diagnostic information that might change the clinical diagnosis in 20%--40% of hyperamylasemic patients.