Authors: Gelenberg AJ, et al.
Title: Comparison of standard and low serum levels of lithium for maintenance treatment of bipolar disorder.
Reference: N Engl J Med 1989;321:1489-93.
Purpose: To compare the effects of standard and low serum concentrations of lithium on relapse rates and side effects in patients with bipolar disorder.
Study design: Randomized, double-blinded trial.
Follow up: Up to 3 years.
Patients: 94 patients (47 standard-range lithium, 47 low-range lithium).
Treatment: Lithium titrated to 0.8–1.0 mmol/L (standard serum concentration) and 0.4–0.6 mmol/L (low serum concentration).
Results: 13% of patients receiving standard-range lithium experienced relapse compared with 38% of patients receiving low-range lithium. Patients receiving low-range lithium had a significantly shorter time to relapse. Risk of relapse was 2.6 times higher in the low-range group. Side effects were more frequent in the standard-range group.