Clinical correlates of the lithium pump.

The active efflux of lithium from erythrocytes, expressed as the rate constant ko, was studied in patients with primary affective disorder and in controls. The authors' data suggest that ko is stable within individuals over time, is inhibited during treatment with lithium carbonate, and may be a good index of lithium toxicity. ko correlates significantly with the lithium erythrocyte/plasma ratio but is seemingly not related to age, sex, or affective disease subtype. Preliminary data suggest that ko may be determined, at least in part, by a genetic factor.