Plasma renin activity, aldosterone and sodium excretion in women with high and low casual blood pressure levels.

Abstract

ABSTRACT. Sixty‐four women not under treatment for hypertension were selected from a population survey and examined with respect to the relationships of BP levels to plasma renin activity (PRA), plasma aldosterone as well as to the 24‐hour urinary excretion of aldosterone, potassium and sodium under strictly defined conditions. The subjects were selected from groups with BP levels above the 95th (group A) and below the 30th percentile (group B). The two groups were age‐matched. PRA and plasma aldosterone were measured after one hour of complete rest in the recumbent position (basal PRA and basal plasma aldosterone), PRA was also measured after four hours of ambulation (upright PRA), as well as four hours after oral administration of 80 mg frusemide (stimulated PRA). The decline of PRA and of urinary aldosterone excretion with increasing age were related to the BP level but not to the menopause. No correlations were found between PRA or plasma aldosterone, on the one hand, and urinary sodium excretion, on the other, in women on random diets. Therefore, it is doubtful whether the correction of PRA levels for urinary sodium excretion is worthwhile unless marked sodium depletion or sodium loading is used. Basal plasma aldosterone showed a high interindividual variability and was not correlated to age or BP.