APPARENT MINERALOCORTICOID EXCESS AND DEFICIENT 11β‐OXIDATION OF CORTISOL IN A YOUNG FEMALE

Abstract

A 19-year-old female, known to have had hypertension and hypokalemic alkalosis since the age of 9 months, was found to have suppressed renin, negligible plasma and urinary aldosterone and low plasma levels of other known sodium-retaining steroids. Despite the normal plasma cortisol the urinary excretion of 17-oxosteroids and 17-oxogenic steroids was low as was the cortisol secretion rate, suggesting a diminished metabolic clearance of cortisol. This was confirmed by the demonstration of a prolonged t_1/2 of ¹⁴C-cortisol. The abnormally high urinary excretion ratios of cortisol to cortisone, tetrahydracortisol to tetrahydrocortisone and 11-hydroxy-aetiocholanolone to 11-oxy-aetio-cholanolone indicate that the diminished cortisol breakdown is the result of deficient 11β-oxidation. Moreover, the urinary excretion of free cortisol was elevated, probably due to diminished tubular reabsorption of cortisol. Hypokalemic alkalosis did not respond to spironolactone, but was partly corrected by amiloride. No response to dexamethasone was observed, but dexamethasone combined with aminogluthetimide normalized blood pressure and serum K. These findings support the involvement of a sodium-retaining, kaliuretic steroid in this rare syndrome.