Lithium ratio in bipolar patients in Isfahan, Iran

BACKGROUND: Lithium is transferred into the intracellul ar space mainly via sodium-lithium counter transport pathway. This pathway is under genetic control and acts variably in different ethnic groups. With respect to possible genetic differences in our target population compared to other populations, this study was designed to obtain knowledge on mean lithium ratio (LR) in this population so as to provide a benchmark for adjusting appropriate dosage of prescribed oral lithium and plasma concentration of lithium in clinical practice. METHODS: In this study, 47 (26 male and 21 female) patients with bipolar disorders treated by lithium alone or in combination with other drugs at least for 2 weeks were selected by simple random sampling. Venous blood samples of selected patients were obtained and plasma and RBC lithium concentrations were measured. Finally, LR was determined using the atomic absorption method. RESULTS: Mean value of LR in the entire target population and in the group treated with lithium alone was 44.4 ± 23.22% and 58.52 ± 14%, respectively. In patients concomitantly treated with lithium and neuroleptic drugs, LR was significantly lower than that in all patients. LR in females was higher than that in males. LR in the group treated with lithium alone was significantly higher than figures reported in Europeans and Americans patients. CONCLUSIONS: These findings suggest that bipolar patients in this geographical zone ofIran should probably be treated with smaller doses of lithium to achieve optimal intracellular therapeutic levels of lithium, compared to levels regarded as therapeutic for Europeans and Americans.