Erythrocyte Lithium and the Erythrocyte: Plasma Lithium Ratio as Indicators of Mood Changes: Preliminary Report

Fifteen patients diagnosed as bipolar I, bipolar II, unipolar, or bipolar I/schizophrenic, and each receiving prophylactic lithium carbonate, were studied for nine months in an outpatient clinic. Every four to six weeks, plasma and erythrocyte (RBC) lithium concentrations and RBC: plasma lithium ratios were monitored and mood scales were recorded. In those patients who showed a change in mood, a positive association was found between decreased RBC lithium concentration and depression ( p = 0.0156), and also between RBC: plasma lithium ratio and depression ( p = 0.0156). No relationship between plasma lithium concentration changes and depression could be determined.