Pathogenesis of hypertension in Cushing's syndrome.
Steroid production, plasma renin activity (PRA) and plasma renin substrate (PRS) were measured in eight patients with hypertension due to Cushing's syndrome of benign origin. Despite elevation of cortisol secretion in all patients, hypokalemia and suppressed PRA was noted in the one subject with a functioning adrenal adenoma. PRA was normal in six patients on an unrestricted sodium intake but was markedly increased in the two patients on low salt diets. PRS was significantly increased during active disease, but decreased substantially with treatment. The absence of uniform hypokalemia and of suppression of renin indicates that mineralocorticoid production could not account for the increase in arterial pressure. It is suggested that glucocorticoid-induced hypertension may be initiated by alterations in vascular responsiveness to pressor agents and that elevated PRS levels may contribute to increase angiotensin formation.