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. 