SUMMARY The paper describes a two-month period of study in four bipolar manic-depressive patients in a metabolic ward. Plasma renin activity, packed cell volume, plasma sodium and potassium were determined at intervals. Twenty-four-hour urinary sodium, potassium and creatinine were also estimated daily. Aldosterone production rate was measured on two occasions for each patient. Three of the patients showed at least one episode each of mania and depression during the study, while the fourth patient, who was receiving prophylactic lithium throughout, had one ten-day depressive episode but was otherwise normal.
No obvious relationship between mood and plasma renin activity was observed, but the group showed a high resting renin activity, a blunted renin response to posture, and inappropriate aldosterone production rates for the renin activity found.
It is postulated that a primary defect in the aldosterone-renin system may be present in bipolar manic-depressive psychosis.