The Role of Aldosterone in the Response to Treatment of Primary Hypertension

The role of the renin-aldosterone axis in mediating responses to antihypertensive treatment was examined in patients with essential hypertension treated with propranolol (n=50) or chlorthalidone (n=50). Control plasma renin activity tended to be predictive of the response to treatment: it correlated with the diastolic blood pressure changes produced by both the renin-lowering agent, propranolol (r=-.43, P less than 0.001), and the diuretic, chlorthalidone (r= .48, P less than 0.001). However, when patients were divided into responders (fall in diastolic blood pressure of greater than 10%) and non-responders, the treatment-induced changes in aldosterone excretion rate appeared to be more important than the changes in renin in determining outcome. During propranolol there was no difference between the renin changes in the responders (n=21) and the non-responders (n=29), but aldosterone fell significantly more (P less than 0.025) in the responders than in the non-responders. Similarly, renin changes during chlorthalidone were not markedly different between the two groups, but the increase in aldosterone excretion in the non-responders was significantly greater (P less than 0.001) than in the responders (n=25). Thus, regardless of the treatment used, responders were characterized by having lower levels of aldosterone during therapy than non-responders. This possible role for aldosterone in influencing blood pressure changes was not related to clinically measurable effects on fluid and electrolyte balance; it has been conjectured that this pressor effect of aldosterone could reflect a direct action in the peripheral circulation.