Plasma aldosterone in newborns and children.

Plasma aldosterone concentrations were determined by radioimmunoassay in 134 healthy newborns and children of both sexes from the first day to 14 years of life. The highest mean value of aldosterone level was found during the first 24 hours of life (79.5 ng/100 ml), with a mean elevation by a factor of 10 in comparison to the results of adults. An age dependent decrease towards the children in the age group 6-14 years was found. The aldosterone concentration of the age group 6-14 years did not differ significantly from the aldosterone level of adults. The question of the origin of the increased aldosterone levels found in newborns and infancy is discussed.