Practicality of a lithium dosing guide

A method of dosing lithium based on a 24-hour serum lithium level obtained after a single 600-mg oral dose of lithium carbonate has been reported to provide a steady-state lithium concentration of 0.6--1.2 mEq/liter. Since this regimen is widely used in clinical practice, the authors designed a study to determine the practicality of the dosing guide. Of 13 patients who followed this dosing protocol, 4 (30.7%) failed to achieve the defined steady-state range. The authors discuss factors that may affect the reliability of the dosing guide.