Normal integrated concentration of aldosterone and plasma renin activity: effect of age.

The integrated concentration of aldosterone (IC-ALDO) and PRA (IC-PRA) was studied in 78 normal subjects ranging in age from 9--50 yr. Whereas the IC-ALDO to IC-PRA were found to decrease with age, the ratio of IC-ALDO to IC-PRA was not affected by age. A significant lowering of the normal range and variance was achieved by measuring the 24-h integrated concentration instead of the concentration in discrete samples.