Erythrocyte accumulation of the lithium ion in control subjects and patients with primary affective disorder

The accumulation of the lithium ion (Li⁺) by erythrocytes relative to the plasma concentration of the cation (referred to as the Li Ratio) was measured both in control subjects and in patients with either unipolar or bipolar affective disorders. In the control subjects, the Li Ratio was measured in two different ways: 1) 21 subjects took lithium carbonate for three weeks and the Li Ratio was measured in vivo; 2) in 28 subjects, the Li Ratio was measured in vitro by a technique described previously. This technique enables an accurate prediction to be made of an individual's Li Ratio in vivo. All the patients received lithium carbonate and had their Li Ratios measured in vivo. As a group, bipolar patients had a mean Li Ratio that was significantly higher than that measured in the control population; unipolar patients did not. The significant difference observed for the bipolar patients was seen either with male or female subjects.