The authors also did not include data regarding serum blood levels of these medications. Consideration of blood levels is essential for several reasons. One cannot conclude that the preceding trials of lithium and carbamazepine were ineffective unless serum levels were adequate. The same is true for the trials involving mood stabilizers in combination. Also, when carbamazepine is used with valproate, it is imperative to carefully monitor levels, since carbamazepine induces both its own metabolism and that of valproate (3). Furthermore, valproate can elevate carbamazepine levels (4).