The basal levels of active and inactive plasma renin concentration in infancy and childhood

Area of Science:

• Pediatric Endocrinology
• Renal Physiology
• Biochemistry

Background:

• The renin-angiotensin-aldosterone system (RAAS) plays a crucial role in blood pressure regulation.
• Understanding developmental changes in the RAAS components, like renin, is vital in pediatric health.
• Plasma renin exists in active and inactive forms, with implications for RAAS regulation.

Purpose of the Study:

• To investigate age-related changes in basal plasma renin activity, active renin concentration, and inactive renin concentration in healthy children.
• To determine the relationship between active and inactive renin concentrations and plasma renin activity.
• To assess the proportion of inactive renin in children and its relation to age.

Main Methods:

• Measurement of basal plasma renin activity (PRA), active plasma renin concentration (PRC), and inactive PRC in 89 healthy children.
• Participants ranged in age from 1 week to 16 years and were in a recumbent position.
• Statistical analysis included correlation coefficients to assess relationships between variables and age.

Main Results:

• A significant age-related decrease was observed for active PRC (r = -0.60), inactive PRC (r = -0.59), and total PRC (r = -0.66) (P < 0.001).
• After adjusting for age, active PRC strongly correlated with PRA (r = 0.81) but showed no significant correlation with inactive PRC (r = 0.18).
• The proportion of inactive renin was not age-dependent, with an overall average of 79% inactive renin.

Conclusions:

• Plasma renin activity and concentration significantly decline with age throughout childhood.
• Active renin concentration is a reliable indicator of plasma renin activity in children, independent of inactive renin levels.
• A substantial proportion of circulating renin in children exists in an inactive form, a characteristic that remains consistent across different ages.