Background: Apparent mineralocorticoid excess (AME) is a rare congenital autosomal recessive disorder resulting from mutations in the HSD11B2 gene, which encodes the kidney isozyme of 11-β-hydroxysteroid dehydrogenase type 2, inactivating circulating cortisol to the less-active metabolite cortisone. Less than 100 cases of AME have been reported in the literature so far. Affected individuals have elevated renal concentrations of cortisol, which can cross-react and activate the mineralocorticoid receptor, leading to aldosterone-like effects in the kidney. AME is usually diagnosed within the first years of life in children presenting with failure to thrive, severe hypertension (HT), low renin and aldosterone levels, profound hypokalemia and hypernatremia. Measurement of urinary free tetrahydrocortisol and tetrahydrocortisone ratio (allo-THF+THF)/THE is important in the diagnosis. AME can also present later in life, in apparent healthy children or adolescents.
Case report: We describe the case of two brothers, aged 14 and 7 years, which were diagnosed during a routine visit as suffering from HT (blood pressure values above the 95th percentile for gender and age; 160/110 mmHg in the first brother and 150/110 mmHg in the second one). They were in good general conditions and their clinical examination was normal. At echocardiography, the oldest one had a moderate left ventricular hypertrophy. As they had no risk factors for primary HT, we performed laboratory and instrumental exams to detect a secondary form of HT. We found hypokalemia (K 2.6 mmol/l) just in the older brother with low levels of both aldosterone (undosable in both children) and renin. The urinary steroid profile revealed a marked increase in the (allo-THF+THF)/THE ratio (6.1; normal value <0.5). Children started spironolactone with a good response.
Conclusion: Our cases suggest that it is important to think about AME also in apparent healthy children or adolescents affected by HT, because the disease can remain unrecognized until late childhood or adolescence. An early diagnosis and a prompt treatment of AME are important to prevent end-organ damage, sudden stroke, cardiac, and renal insufficiency.
20 - 22 Sep 2014
European Society for Paediatric Endocrinology