Plasma and erythrocyte cations in affective illness.

Plasma and erythrocyte cations (sodium and magnesium) were studied in groups of patients with an affective disorder and in normal subjects. Baseline determinations were obtained before initiation of treatment for mania or depression. In a subgroup of patients, sequential measurements of cations were made during treatment with lithium carbonate. No differences were found in intraerythrocyte sodium or magnesium among any of the patient groups and controls. Patients with a primary affective disorder had significantly higher plasma sodium than control subjects. Neither baseline cation concentrations nor changes in cation concentration during treatment with lithium correlated with treatment response. Gender was shown to be a significant variable affecting intraerythrocyte cation concentrations.