Aldosterone concentrations in dehydrated infants

The mean serum aldosterone concentration of 37 infants with acute gastroenteritis and dehydration was markedly elevated on admission (mean +/- SE 94.3 +/- 12.1 ng/ml) and approximated to normal values (18.2 +/- 3.7 ng/ml) following recovery from the acute disease (t=3.56 p less than 0.005). Serum aldosterone levels were significantly positively correlated with the percent weight loss (r=0.41, p less than 0.05) and with the blood urea nitrogen levels (r=0.55, p less than 0.001). There was no correlation between either serum sodium levels or blood osmolarity and aldosterone concentrations. Serum potassium levels were positively correlated with aldosterone levels (r=0.53, p less than 0.001). These findings indicate that small infants when dehydrated respond appropriately with elevated aldosterone levels. The amount of body fluid depletion and hyperkalemia are the major factors determining the amount of aldosterone response.