The relation between aldosterone concentrations in plasma and saliva during pregnancy

The concentrations of aldosterone and glucocorticoids (cortisol + cortisone) were measured in saliva and plasma samples obtained from healthy women during early (11-19 weeks), mid (24-29 weeks) and late (32-37 weeks) pregnancy. There was a progressive increase in mean aldosterone levels in both saliva and plasma throughout pregnancy, though at each stage of pregnancy the range was very wide. Glucocorticoid levels increased up to mid-pregnancy and then remained constant. At no stage were aldosterone and glucocorticoid levels significantly correlated. The proportion of free (non-protein bound) aldosterone in plasma, and the saliva:plasma ratio of aldosterone did not differ from the non-pregnant range at any stage of pregnancy. We conclude that measurement of aldosterone concentration in saliva is a convenient and valid method for the estimation of plasma free aldosterone in pregnancy and so provide a non-invasive technique for assessing aldosterone status throughout pregnancy.