Normal plasma renin activity in low renin hypertension.

Abstract

Plasma renin activity (PRA) was measured every 4 h during a 24-h period of continuous recumbency in 10 patients with essential hypertension. All had maximum values at 12 midnight, 4 AM or 8 AM. Analysis of our date and that of others indicates that in some patients with "low renin" hypertension (LRH) these noctural peaks are of normal magnitude, occasionally exceeding values obtained after four hours of erect posture. Sleep-induced renin release in these patients is not suppressed despite blunted responses to other stimuli. This suggests that the ability to synthesize and release renin may be normal in these patients. Such peaks were not obserived in all LRH subjects, however. The area enclosed by the recumbent PRA curve was also normal in some, but not all patients with LRH. Low renin hypertension may not be a homogeneous disorder.