A Rare Encounter: Severe Hypertension and Hypokalemia Due to an Apparent Mineralocorticoid Excess

Background: Apparent mineralocorticoid excess syndrome (AME) is an extremely rare autosomal-recessive genetic disorder due to deficiency in 11-beta-hydroxysteroid dehydrogenase enzyme type 2 isoform (11-beta-HSD2) that converts cortisol to cortisone. The resultant high cortisol level (100-fold higher than aldosterone) avidly binds to and activates the mineralocorticoid receptors leading to hypertension and hypokalemia. Case: A 14-year-old girl presented with severe hypertension, unprovoked hypokalemia with high urinary potassium output, and metabolic alkalosis. She did not have a history of parenteral disease, chronic licorice ingestion and lung tumors by FDG-PET scan. Diagnosis was established by; 1) a high 24-hour urinary cortisol to cortisone ratio (>18), 2) low serum levels of renin, aldosterone, 11-beta-HSD and adrenocorticotrophic hormones, and 3) genetic testing showing homozygous pathogenic variants in HSD11B2 gene. Treatment: With low-salt diet and daily Amlodipine 5 mg, Amiloride 50 mg and Spironolactone 50 mg, stabilized her disorders up to 6 months of follow-up. Conclusion: AME should be considered in children with severe hypertension and unprovoked hypokalemia.