Control of plasma aldosterone in infancy and childhood. A study of plasma renin activity, plasma cortisol and plasma aldosterone.

In order to elucidate the main factors controlling plasma aldosterone in infancy and childhood, plasma renin activity (PRA), plasma cortisol (PC, as a parameter of ACTH activity), plasma aldosterone (PA) and serum sodium and potassium were measured simultaneously in 84 healthy children (62 recumbent, 22 upright) ranging in age from 6 days to 16 years. 10 healthy male students served as adult controls. As compared to the controls, PRA levels were significantly higher in the children up to the age of 12 years. PA was also elevated in most children; the highest values for PA and for PRA were observed during the first 4 years of life. A significant positive correlation between PRA and PA (n = 84, r = 0,62, p less than 0.001) was found. There were no significant differences in serum sodium or potassium or in PC. All PC values were - with one exception - within the range found in healthy adults. Our results indicate that high PA values are freuqently observed in healthy children. They are mainly caused by elevated PRA. The physiological significance of increased activation of the renin-angiotensin-aldosterone system in infancy is not yet clear.