[Hyperaldosteronism]. / Hyperaldosteronismus.

Aldosterone is produced in the adrenal cortex and governs volume and electrolyte homeostasis. Hyperaldosteronism can occur either as primary aldosteronism (renin-independent) or secondary aldosteronism (renin-dependent). As the commonest cause of secondary hypertension, primary aldosteronism is associated with increased cardiovascular risk. Its most prevalent subtypes are aldosterone-producing adenomas as the most frequent unilateral form and bilateral hyperaldosteronism. Unilateral hyperplasia, familial hyperaldosteronism and aldosterone-producing carcinoma are rare. The aldosterone/renin ratio serves as a screening parameter for primary aldosteronism. If this ratio is elevated, confirmatory testing and adrenal imaging are performed. Adrenal venous sampling is considered the gold standard for the distinction of unilateral from bilateral disease. Unilateral disease can potentially be cured by adrenalectomy, whereas patients that are not candidates for surgery or have bilateral disease are treated with mineralocorticoid receptor antagonists. Over the past 10 years, somatic mutations in ion channels or transporters have been identified as causes of aldosterone-producing adenomas and so-called aldosterone-producing cell clusters (potential precursors of adenomas and correlates of bilateral hyperplasia, but also of subclinical hyperaldosteronism). In addition, germline mutations in overlapping genes cause familial hyperaldosteronism. Secondary hyperaldosteronism can occur in patients with hypertension treated with diuretics or in renal artery stenosis.

An Update on Familial Hyperaldosteronism.

Familial forms of primary aldosteronism have been suggested to account for up to 6% of cases in referral centers. For many years, the genetics of familial hyperaldosteronism remained unknown, with the notable exception of glucocorticoid-remediable aldosteronism, due to unequal crossing over and formation of a chimeric 11ß-hydroxylase/aldosterone synthase gene. Over the past 5 years, mutations in 3 additional genes have been shown to cause familial forms of primary aldosteronism. Gain-of-function heterozygous germline mutations in KCNJ5, which encodes an inward rectifier potassium channel, cause autosomal dominant syndromes of PA and hypertension with or without adrenal hyperplasia. Germline mutations in CACNA1D, which codes for an L-type calcium channel, have so far only been found in 2 cases with a syndrome of primary aldosteronism, seizures, and neurologic abnormalities. Both KCNJ5 and CACNA1D mutations in familial hyperaldosteronism were only discovered following identification of similar or identical somatic mutations in aldosterone-producing adenomas. In contrast, a recent exome sequencing study identified germline mutations in CACNA1H (a T-type calcium channel), previously undescribed in adenomas, in 5 unrelated families with early-onset primary aldosteronism and hypertension, without any additional shared symptoms. Future exome or genome sequencing studies are expected to shed light on the genetic basis of many cases of familial hyperaldosteronism that remain unexplained.