Salivary amylase in cystic fibrosis: a marker of disordered autonomic function

Total serum amylase was determined in 83 patients with cystic fibrosis (CF) (14 of whom had no steatorrhea), 21 control patients, and 6 patients with Shwachman's syndrome. Patients with CF who had steatorrhea and therefore lacked pancreatic function had the same serum levels pre- and postprandially as the control subjects, whereas patients without steatorrhea and, therefore, with evidence of pancreatic function, had significantly higher levels. The patients with Shwachman's syndrome had significantly lower total serum amylase than the three other patient groups. Only the patients with Shwachman's syndrome demonstrated a significant postprandial rise in activity. Only the salivary isoenzyme was detected in patients with Shwachman's syndrome or CF and apparently absent pancreatic function, whereas CF patients without steatorrhea had both salivary and pancreatic isoenzymes. These results demonstrate that patients with CF have an increase in circulating salivary amylase isoenzyme whereas patients with Shwachman's syndrome do not. The increase probably reflects an autonomic hyperstimulation of salivary secretion which is primary to CF, and unrelated to the state of pancreatic activity.