On the significance of the erythrocyte lithium to plasma lithium ratio.

Correlations between the ratio of erythrocyte to plasma lithium (Le/Lp) and clinical status have been reported by some authors and disputed by others. Examination of the literature on Le/Lp and erythrocyte physiology suggests that Le/Lp is determined by peripheral pharmacokinetic parameters and has no direct relationship to central pathophysiology. Because of this, and because of inconsistencies between studies reporting correlations of the ratio with clinical status, such correlations probably cannot illuminate either the pathophysiology of affective illness or the mode of action of lithium.