Reciprocal Variations in Urinary Cortisol and Aldosterone in Response to the Sodium-Depleting Influence of Hydrochlorothiazide and Ethacrynic Acid in Humans

In a prior study the rate of urinary cortisol excretion increased and aldosterone excretion decreased following the administration of chronic oral salt loads. In 2 of these subjects the cortisol secretion rates also rose. In the present study reciprocal relationship between cortisol and aldosterone excretion also prevails, aldosterone excretion rising and cortisol excretion declining in response to the diuretic action of hydrochlorothiazide and ethacrynic acid. The cortisol secretion rate was definitely decreased in 1 subject, but only suggestively lowered in 2 others. The possibility that the decline in cortisol excretion could be due to induced changes in renal clearance or in the metabolism of cortisol has not been eliminated from consideration. However, because of the indications that cortisol excretion may be a highly sensitive indicator of cortisol secretion in this circumstance, it is tempting to speculate that these changes in cortisol excretion reflect a mechanism in which shifts in cortisol secretion may actively participate in the regulation of electrolyte metabolism.