Findings suggest, according to the authors, that bipolar patients in the central zone of Iran 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. Lithium ratio (LR) in bipolar patients treated with lithium alone was significantly higher than figures reported in Europeans and Americans patients.

LR is the ratio of red blood cell lithium to plasma lithium concentration. Lithium is transferred into the intracellular space mainly via sodium-lithium counter transport pathway.
This pathway is under genetic control and acts variably in different ethnic groups.
LR is significantly higher in women (54.57 +/- 25.08) than in men (36.18 +/- 18.22).
In patients concomitantly treated with lithium and neuroleptic drugs, LR was significantly lower than that in all patients.

N= 47 (26 male and 21 female) bipolar patients; descriptive cross-sectional study with a convenience sample of bipolar outpatients and inpatients presenting to psychiatric referral centers of Isfahan (Nour, Alzahra and Farabi Hospitals), central Iran.

(Hashemi et al. 2006)