Relationship between clearance of lithium, potassium and sodium in human mixed saliva

Samples of saliva were collected from healthy subjects given a test dose of lithium carbonate. Lithium clearance in saliva was well related to salivary potassium clearance but not to salivary sodium clearance. Stimulation of adrenocortical activity by changing from the recumbent to the upright posture caused salivary sodium clearance to fall, but failed to affect the clearance of lithium and potassium in saliva. The findings show that the secretion of lithium in saliva resembles potassium secretion more than sodium secretion.