[The significance of the serum lithium level for lithium therapy of phasic psychoses (author's transl)].

Lithium is an effective substance for the treatment of frequently recurring manias and depressions. But its use requires some precautionary measures which must be carefully attended to. Thus, the initial dose must be low. Then the serum lithium level must be determined after one week. The best time to take the blood sample is about 12 hours after the last dose of lithium. The dosage is adjusted according to the serum lithium level. Subsequent adjustments are frequently necessary during the first few weeks of treatment until the optimal serum lithium level for the individual patient has been found.