Prediction of lithium maintenance doses using a single point prediction protocol.

Conflicting reports regarding the utility of a previously described single point prediction dosing method for lithium prompted the present study's reexamination of the relationship between a single point lithium concentration and the lithium maintenance dose. Seventeen informed, adult patients with affective illness were studied. The relationship between their 24-hour lithium concentration after a test dose and the maintenance dose was significant, hence confirming earlier reports. In addition, more confident relationships were noted when steady state range concentrations for lithium prophylaxis (0.41 to 0.89 mEq/liter) and for treatment of acute mania (0.9 to 1.27 mEq/liter) were analyzed separately. Maintenance dose predictive equations were generated for these lithium steady state ranges from a 24-hour single point level after a 1200-mg test dose. The clinical usefulness of the new relationships observed for maintenance dose prediction must await prospective testing.