Aldosterone excretion rates in children and adults during sleep

The present study undertook to examine aldosterone excretion during sleep as an integrated measurement of aldosterone production. A 24-hour urine collection was divided into awake and sleep fractions. Urinary aldosterone and electrolyte excretion were measured in 26 healthy children (mean age, 8.9 +/- 1.9 [SD] years) and 28 adults (mean age, 29.9 +/- 9.5 years). Aldosterone excretion in children was 5.6 +/- 3.9 (SD) micrograms/g creatinine during the awake period, which was significantly different from the 3.9 +/- 4.1 micrograms/g creatinine value recorded during sleep (p less than 0.002). In adults, awake aldosterone excretion was significantly greater than that during sleep; 4.9 +/- 2.7 versus 3.2 +/- 1.6 micrograms/g creatinine (p less than 0.001). Sleep aldosterone excretion values were highly correlated with the corresponding 24-hour aldosterone excretion values (r = 0.85, p less than 0.001) in children and in adults (r = 0.64, p less than 0.001). Sleep aldosterone excretion was correlated with 24-hour potassium excretion (p less than 0.02) only in children. Sleep aldosterone excretion correlated with neither sleep nor 24-hour sodium excretion in children or adults. Sleep electrolyte excretion rates were highly correlated with 24-hour excretion rates in both children and adults. Dexamethasone, 1 mg, administered the night before to suppress the normally high morning levels of endogenous adrenocorticotropic hormone, had no discernible effect on sleep aldosterone excretion. These results indicate that measurement of aldosterone excretion in an easily collected sleep urine sample provides a reliable index of aldosterone production in children and adults.