The Influence of Estrogen and Progesterone on Aldosterone Excretion*†

The following findings were obtained which bear on the mechanisms responsible for the rise in aldosterone secretion and excretion during pregnancy. In 7 of 8 patients given estrogen, urinary aldosterone remained within normal limits although the concentration of plasma free 17-hydroxycorticoids rose to pregnancy levels. In 6 patients given progesterone, there was a rise in aldosterone excretion. In the 2 oldest members of this group the increase in aldosterone excretion was modest and there was no reversal of the progesterone- induced sodium diuresis. In the 4 younger subjects, urinary aldosterone rose to well above the normal range in association with a prompt reversal of the progesterone induced natriuresis. In the 2 of these 4 subjects in whom aldosterone secretion was measured there was an increase which paralleled the increase in excretion of the hormone. It is suggested that the rise in secretion and excretion of aldosterone during pregnancy is largely a consequence of increased progesterone secretion.