Plasma renin concentration during lithium therapy.

Plasma renin concentration was determined in patients given lithium treatment. In longitudinal study plasma renin concentration was determined in nine patients before the start of lithium treatment and at intervals during 3 months of treatment. In a transversal study, 18 patients given lithium treatment for 2--20 years were compared with 11 control persons. In the longitudinal study, plasma renin concentrations did not, during lithium treatment, deviate significantly from pre-treatment values. In the transversal study, values in the lithium treated patients did not differ significantly from values in the control group. There were no correlations, in the transversal study, between serum lithium concentrations and plasma renin concentrations. Our study indicates that the plasma renin concentration remains unaffected by lithium administered in nontoxic doses.