The renin-angiotensin-aldosterone system in normal 85-year-old people

Active and total plasma renin concentration, as well as plasma angiotensin II, aldosterone and renin substrate concentrations were measured in venous blood samples from 17 normal 85-year-old people at rest. No discernible sex-related differences were seen. Active plasma renin and plasma aldosterone concentrations were significantly lower in the old people compared to a group of normal 40-year-old people. Plasma angiotensin II concentration showed no decrease with increasing age. Active plasma renin concentration constituted approximately 20% of total plasma renin concentration, with a significant correlation between the two renin moieties. The values for plasma renin substrate concentration are similar to those reported for younger age groups. The lack of standardization of methods severely hampers inter-laboratory comparisons of both active plasma renin and total plasma renin concentrations.