[Study of factors affecting the renin-angiotensin-aldosterone system in the premature infant]. / Studio dei fattori che influenzano il sistema renina-angiotensina-aldosterone (RAA) nel bambino prematuro.

ABSTRACT

Renin-angiotensin-aldosterone system (RAA), Na-K dietary intake and Na-K urinary excretion in 36 premature babies have been investigated. The plasmatic renin activity (PRA) and plasmatic aldosterone level (P-aldo) resulted significantly increased in comparison with children previously studied, 20 days - 23 months old (p less than 0,01). P-aldo demonstrated, in premature babies, a negative correlation with Na-K intake and urinary excretion (p less than 0,001 and less than 0,01 respectively); in the groups nourished with maternal milk or "adapted" formulae P-aldo mean value was significantly more elevated than in the group nourished with formulae "unadapted" (p less than 0,01). A different Na dietary intake seems to be the most important factor influencing P-aldo level also in premature babies. No correlation between PRA - electrolyte excretion was found in any group. The main factor influencing PRA seems to be the age of infants as well as, probably, other hemodynamic mechanisms.