Radiation-induced xerostomia in cancer patients. Effect on salivary and serum electrolytes.

Saliva and serum electrolyte concentrations were monitored in 30 patients given a course of xerostomia-producing cancer radiotherapy. The mean flow rate of stimulated whole saliva decreased 83.3% during a 6-week treatment period. The striking reduction in saliva output was accompanied by significant increases in saliva Na+, Cl-, Ca++, Mg++ and Prot.- concentrations and by a decrease in saliva HCO3- content. The xerostomic saliva was more concentrated and had a greater salinity than the pretreatment saliva in each instance. In contrast, none of the serum electrolytes measured was significantly altered by the subtotal salivary shutdown.