Essential arterial hypertension: plasma and urinary aldosterone alterations.

We studied 52 patients with mild to severe essential arterial hypertension and ranging in age from 30 to 60 years (average, 44). Various biochemical and endocrinologic parameters were studied, with special emphasis on plasma aldosterone and urinary aldosterone. At the same time, a control group of 30 normal subjects (nonhypertensive) were studied under the same conditions. Both groups were carefully selected. Results indicated that the hypertensive group demonstrated a marked increase in plasma aldosterone levels (P less than .01) and an increase in the coefficient of plasma aldosterone/plasma renin activity (P less than .01). This indicates inadequate secretion of plasma aldosterone. There were no significant changes in the urinary aldosterone. Statistically significant changes were found in plasma renin activity (P less than .001) and plasma aldosterone (P less than .001) when the hypertensive patients were divided into two age groups, those under 45 and those over 45. These changes were not found in the normal subjects in the same age groups, indicating that age is an important influence on the renin-aldosterone system in hypertensive patients, and leads to variations in this hormonal axis similar to those observed in normal elderly subjects.