Postural Augmentation of Plasma Renin Activity

We have previously reported that upright posture is a potent stimulus for increasing plasma renin activity in man.¹⁻⁴Clinical application of this finding has proven to be of great value in demonstrating the suppression of renin activity which is always associated with primary aldosteronism.³,⁴In renovascular hypertension, levels of renin activity or of renin concentration have been measured by others,⁵⁻¹¹but, by the methods and techniques 11 ployed,⁵,⁶ ⁸,¹¹it has not been possible consistently to demonstrate elevations of renin activity even in patients with functionally significant lesions of the renal artery. We have already indicated briefly¹²,¹³that, with proper attention to dietary sodium and to the influence of posture, the level of peripheral plasma renin activity can be made to be critical in the diagnosis of renovascular hypertension. The purpose of this communication is to record data which demonstrate that the normal response to