Apparent mineralocorticoid excess - A rare cause of endocrine hypertension

Abstract

Background: Endocrine causes of hypertension constitute a very small percentage of patients with secondary hypertension. Apparent mineralocorticoid excess (AME) is a rare genetic form of young-onset secondary hypertension. Clinical Description: We present a case of a 16-year-old boy who was diagnosed with hypertension at 5 years of age, had recurrent episodes of hypokalemic paralysis, and deranged renal function for 1 year. Hypertension was uncontrollable with multiple antihypertensive agents until an aldosterone antagonist (spironolactone) was added. Clinical history and evaluation could not identify any secondary causes of hypertension. There was no significant family history. Growth and puberty were age-appropriate. Management and Outcome: Endocrine workup was planned considering hypokalemia and metabolic alkalosis. This demonstrated hyporeninemic hypoaldosteronism and raised the possibility of AME and Liddle syndrome. Clinical exome sequencing revealed a probable diagnosis of AME due to a novel homozygous variant (c.911A>G) in HSD11B2 gene. Sanger sequencing confirmed heterozygosity of the same variant in both parents. Conclusion: A novel homozygous variant was found in HSD11B2 gene in a subject with early-onset hypertension associated with hypokalemic metabolic alkalosis, establishing the diagnosis of AME. The use of an algorithmic approach and individualized planning of genetic studies can help in early diagnosis. This helps clinicians to select the appropriate antihypertensive drug, attain good control, and prevent the development of end-organ damage. A high index of suspicion should be kept for AME and other hyporeninemic hypoaldosteronism conditions in the case of early-onset hypertension.