A decreased metabolic clearance rate of aldosterone, a possible mechanism of development of hyperaldosteronism in benign, uncomplicated essential hypertension. Circulation

clearance rate, and/or plasma concentration were de-termined in 16 patients with benign, uncomplicated essential hypertension and compared with those of con-trol subjects. The mean metabolic clearance rate of aldosterone in 10 patients was significantly (P < 0.001) lower (mean 867 liters of plasma/day per m2 ±270 sD) than in a group of 7 healthy subjects (mean 1480 liters/ day per m2 ±265 sD). Secretion rates in 13 patients (including the 10 already mentioned) tended to be low (83 +43 vs. 109 +54 ug/day) and plasma concentrations tended to be high (13.6 ±4.6 vs. 7.5 ±4.8 ng/100 ml), but neither of these differences was statistically sig-nificant. The lower metabolic clearance rate could account for elevated plasma concentrations of aldosterone even when the secretion rate is normal or low. Measure-ment of secretion rate or urinary excretion only is therefore insufficient to establish the presence and/or mode of evolution of hyperaldosteronism. Failure of the aldosterone secretion to adapt fully to a decreased aldosterone metabolic clearance rate (MCR) could ex-plain the state of relative hyperaldosteronism in patients with benign essential hypertension, even when the secretion rate and the urinary excretion rate are in the normal range