The renin-angiotensin-aldosterone system in infancy and childhood in basal conditions and after stimulation

Abstract

Plasma renin activity (PRA), aldosterone (PA), sodium and potassium concentration were measured in 107 healthy infants and children under basal conditions of normal diet and recumbency. Urinary aldosterone (U_Aldo), sodium and potassium were also measured (n=51). A significant (Pr=-0.67), PA (r=-0.67), and U_Aldo (r=-0.56) was observed, with a striking scatter of values especially in infancy. The renin-angiotensin-aldosterone system (RAAS) was also studied after stimulation by standardised sodium restriction during 4 days, followed by acute postural change (n=40). After salt restriction a rise of PRA and U_Aldo was noted, but a rise in PA could not be demonstrated in children aged 0–6 months. The influence of postural change on the RAAS seems more important in older children. The reported values not only in basal but also in stimulated conditions allow study of the RAAS in diseases such as salt loss and hypertension.