Saliva lithium levels in children: their use in monitoring serum lithium levels and lithium side effects.

The reliability of saliva lithium levels in monitoring serum lithium levels in children taking lithium has rarely been studied, despite the potential usefulness of such a study and despite a number of adult studies focusing on the technique. In a study of 61 aggressive school-age children diagnosed as undersocialized, aggressive conduct disorder, a subsample of 21 children received lithium. Saliva lithium levels aided in monitoring side effects, and in 15 of the 21 children simultaneous saliva and serum lithium levels were done. These were highly correlated (r = 0.83) and the saliva to serum ratio was 2.53 across subjects. The results indicate that future work with larger numbers of children should study the ratio of saliva to serum lithium levels. Adult studies have shown that there is too great a variability in saliva to serum lithium level ratios to support the use of a fixed saliva to serum lithium ratio. This may not be the case in children. Seventeen children from the lithium subsample experienced 41 lithium-related side effects. Most children suffered side effects on relatively high doses of lithium, and those few who experienced side effects on low dosage had saliva lithium levels that were proportionately high. However, it remains unclear whether saliva lithium can be used to monitor side effects.