Metabolic Studies on Hypertensive Patients with Suppressed Plasma Renin Activity Not Due to Hyperaldosteronism

Abstract

Metabolic data obtained during sodium depletion (10-mEq Na, 90-mEq K diet plus thiazide) from 13 hypertensive patients (HT) with low plasma renin activity (PRA) were compared with data from 15 normotensive subjects and three patients with renovascular hypertension (RHT). With Na depletion plasma renin activity and urinary aldosterone excretion increased promptly in NT and RHT. In contrast, PRA in HT after 5 days of Na depletion was only one third that of the NT after 2 days of depletion, and aldosterone excretion did not change significantly. This depressed renin and aldosterone response in HT can be overcome by extending the depletion period and administering spironolactone. In HT, Na and loss of weight was significantly lower than in NT. HT Negroes retained more potassium than HT whites and four out of seven NT Negroes and none of eight NT white subjects had a positive K balance. The hypertension of patients with low PRA appears to be due to genetic or environmental factors or to both.