Comparison between saliva and serum lithium concentrations in patients treated with lithium carbonate

Abstract
The relation between serum and saliva Li concentration was studied in patients treated with lithium carbonate. In 23 patients a highly variable saliva/serum ratio was found in simultaneous saliva and serum samples. Of 5 patients studied during a period of 4-8 wk, three showed a high fluctuation in saliva/serum Li ratio. Saliva Li concentrations in 20 patients varied unexpectedly in a 2nd sample produced after 15 min. The saliva Li level was considered unreliable as a prediction of the serum Li level in patients treated with lithium carbonate.