Lithium erythrocyte:Plasma ratio in primary affective disorder

Abstract

The purpose of this paper is to discuss the metabolism of the lithium ion, particularly the erythrocyte-plasma lithium ratio, in relation to clinical studies of affective disorder. The chronic administration of lithium salts has been shown to be effective in the long-term management of patients with recurrent affective illness. However, the mechanism of action of lithium ion relating to its therapeutic efficacy is unknown. Recent studies of lithium ion metabolism have focused on the ratio of lithium ion in erythrocytes to plasma. 1–5 The erythrocyte red blood cell (RBC) is used as a model for intracellular lithium metabolism, and the ratio of lithium ion concentration in RBCs to plasma has been shown to be under genetic control. 4,6 Furthermore, it has been reported that patients who demonstrate an antidepressant response to lithium administration have higher RBC-plasma lithium ratios, although not all studies agree. 1,3,5 Also, studies have suggested that women with affective disorder may have higher RBC-plasma lithium ratios than women controls or males with manic depressive illness. 2