Saliva lithium levels for monitoring lithium prophylaxis of manic depressive psychosis.

The usefulness of salivary lithium values for monitoring long-term lithium prophylaxis was studied in 60 patients on lithium therapy. A total of 99 pairs of saliva and serum samples were obtained, and the correlation between serum and salivary lithium levels (r = 0.73) was found to be significant at the 1% level. The ratio of salivary serum levels to that of serum was found to range from 1.77 to 6.68. The ratio of 51% of the samples was between 3 and 3.99. It is therefore suggested that it is important to identify the subgroup of patients who show better correlation of salivary and serum lithium levels and use each individual's ratio to monitor only his lithium therapy.