Renin-angiotensin-aldosterone system in the healthy infant and childRenin-angiotensin-aldosterone system in the healthy infant and child
Faculty of Pharmaceutical, Biomedical and Veterinary Sciences. Pharmacy
1979New York, N.Y., 1979
Kidney international / International Society of Nephrology. - New York, N.Y.
16(1979):2, p. 196-203
Renin-angiotensin-aldosterone system in the healthy infant and child. Plasma renin activity (PRA), plasma aldosterone concentration (PAldo), and urinary aldosterone 18-oxoglucuronide excretion (UAldoV) were studied in 69 healthy children, aged 3 months to 15 years, in basic conditions. In 49 of them, PRA and PAldo were also measured after stimulation with oral furosemide and tilting. PRA, PAldo, and UAldo V showed a significant negative correlation with age (P < 0.001) and a greater variation in the youngest age groups. No correlation could be found between PRA or PAldo and the sodium excretion per kilogram of body weight per 24 hours for the total of subjects as well as within each age group. An age-independent correlation between PAldo, but not PRA, and urinary potassium was observed. After correction for age, there was no significant relationship between PRA and PAldo or between plasma sodium or potassium and PRA or PAldo. It is speculated that a lower sodium turnover, as evaluated from the sodium excretion, is probably not the most important cause of the increased PRA or PAldo values, at least within the range of sodium intake in these subjects. As suggested by the results of principal component analysis on correlation matrices, age (and height, surface area) seems to be the most important factor. By what mechanism this factor influences the renin-angiotensin-aldosterone system is at present unclear. Furthermore, in the younger children, the analysis suggests that variables other than age are also involved. After stimulation with furosemide and tilting, there was an increase of the mean PRA and PAldo values. The increase of percentage was greatest in the older age groups where the lowest basic values were found. A positive correlation was found between PRA and systolic as well as diastolic blood pressure: the correlation disappeared after correction for age.