Endocrine Abstracts

Introduction: The syndrome of apparent mineralocorticoid excess (AME), a genetic disorder, resembles findings similar to those in primary aldosteronism, but aldosterone levels are low. AME is due to deficiency in the 11-beta-hydroxysteroid-dehydrogenase-enzyme-type-2 isoform (11-beta-HSD2), which normally converts cortisol to cortisone to prevent its mineralocorticoid activity at the aldosterone-sensitive sites. The deficiency in 11-beta-HSD2 leads to marked elevation in net mineralocorticoid activity caused by unconverted cortisol.

Case report: 50-years old woman was hospitalised after collapse. She had had arterial hypertension for 10 years (bisoprolol 5 mg/day, perindopril/indapamide 8/2.5 mg/day). At the presentation she was hypotensive 96/64 mmHg, mildly Cushingoid, BMI 28 kg/m². Initial laboratory results: s-K 2.44 mmol/l, spot u-K 56 mmol/l, blood pH 7 440. Patient’s medical records revealed, that hypokalaemia had developed after 2001 and had been worsening gradually. After correction of hypokalaemia primary aldosteronism was excluded (PRA 0.015 nmol/l, aldosterone 0.22 nmol/l, after saline infusion aldosterone suppressed to 0.08 nmol/l). Cushing’s disease was confirmed (s-ACTH: 5.31 pmol/l, cortisol after standard 2-day 2-mg dexamethasone test: 213 nmol/l, late evening cortisol: 157 nmol/l, pituitary MRI: 3×4 mm microadenoma, IPSS: a central-to-peripheral plasma ACTH-gradient of 17.5, and left to right ACTH-ratio of 2.37 before CRH administration). Since mild Cushing’s disease couldn’t explain severe hypokalaemia additional underlying cause was suspected. After exclusion of licorice ingestion and adrenocortical tumour, the AME was confirmed by undetectable free-cortison levels in urine measured by liquid-chromatography–tandem mass-spectrometry in two consecutive 24-h urine samples (free cortisol 60.44 and 61.27 nmol/l, free cortison two-times undetectable). Spironolactone was introduced. With the dose of 150 mg/day the patient is normokalaemic, and the hypertension is well controlled by additional bisoprolol 5 mg/day and perindopril 4 mg/day.

Conclusion: 11-beta-HSD2 deficiency is a rare cause of hypertension and hypokalaemia. Presented case report is of special interest showing that mild Cushing’s disease has unmasked the underlying enzyme deficiency. Genetic testing is in progress. Transsphenoidal microadenomectomy is planned.