Parotid gland function in children with cystic fibrosis and child control subjects.

Parotid saliva was collected from 22 children with cystic fibrosis (CF) and 
21 control children. Stimulation was by 0.1 ml 5% citric acid 
on the tongue every 15 sec over a period of 10 
min, and samples were collected for 2-min intervals. Stimulated saliva showed 
a lag period of low amylase release, and an activated period 
of higher amylase release. The major difference between CF and child 
control parotid saliva was in the elevated calcium concentrations in CF 
subjects. Flow rate and amylase, although higher in the CF group, 
were not raised to a statistically significant level. There were higher 
mean values for sodium and inorganic phosphate in CF children but 
statistical significance was minimal. Potassium values were almost identical in CF 
and control saliva. In the activated parotid saliva samples of both 
control and CF subjects there were positive correlations between flow rate 
and calcium, flow rate and sodium, anylase and calcium, and sodium 
and calcium, and negative correlations between sodium and potassium. The parotid 
function test has no value as a diagnostic test for cystic 
fibrosis, as even calcium values show too much overlap with control 
saliva to be of diagnostic worth. 