The Basal Levels of Active and Inactive Plasma Renin Concentration in Infancy and Childhood

1. Basal plasma renin activity, active and inactive plasma renin concentration were measured in 89 healthy recumbent children aged between 1 week and 16 years.

2. A significant (P<0.001) age-related decrease for active (r = −0.60), inactive (r = −0.59) and total renin concentration (r = −0.66) was observed.

3. After correction for the influence of age, active renin concentration correlated with plasma renin activity (r = 0.81), but not with inactive renin concentration (r = 0.18).

4. The proportions of active and inactive renin were not related to age, and the overall percentage of inactive renin was 79%.