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.