Metabolic and Blood Pressure Responses to Hydrocortisone in the Syndrome of Apparent Mineralocorticoid Excess*

A syndrome of low renin hypertension in childhood with apparent mineralocorticoid excess associated with a defect in the peripheral metabolism of cortisol has been described previously in 2 patients. In these patients, decreased secretion rates of glucocorticoids, mineralocorticoids, and sex steroids have been demonstrated. In a 10(10/12)-yr-old girl with this disorder, continuous iv administration of hydrocortisone in doses of 5, 10, 15, and 20 mg/day resulted in an increase in blood pressure and a decrease in serum potassium concentration. The addition of spironolactone during the continued administration of 20 mg/day hydrocortisone did not result in a decrease in blood pressure. Withdrawal of hydrocortisone and continued administration of spironolactone alone resulted in a decrease in blood pressure, a rise in serum potassium concentration, and a fall in serum sodium concentrations. These studies suggest that an abnormality in cortisol action or metabolism causing cortisol to behave as a potent mineralocorticoid may account for this syndrome of apparent mineralocorticoid excess.