Rare hypoaldosteronism

Rare hypoaldosteronism (Orphanet code 181419) is a group of uncommon endocrine disorders characterized by deficient production or impaired action of aldosterone, the primary mineralocorticoid hormone produced by the adrenal glands. Aldosterone plays a critical role in regulating sodium and potassium balance and maintaining blood pressure through its action on the kidneys. When aldosterone is deficient or its signaling is impaired, patients may develop hyperkalemia (elevated blood potassium levels), hyponatremia (low blood sodium levels), metabolic acidosis, dehydration, and hypotension (low blood pressure). These electrolyte disturbances can be particularly dangerous in neonates and infants, potentially leading to life-threatening salt-wasting crises. Rare hypoaldosteronism encompasses several distinct subtypes, including isolated aldosterone synthase deficiency (due to mutations in the CYP11B2 gene), familial hyperreninemic hypoaldosteronism, and pseudohypoaldosteronism (types 1 and 2), where aldosterone levels may be normal or elevated but the kidneys fail to respond appropriately. The clinical presentation varies depending on the underlying cause, ranging from severe neonatal salt-wasting to milder forms presenting later in life with persistent hyperkalemia. Diagnosis typically involves measurement of serum electrolytes, plasma renin activity, and aldosterone levels, along with genetic testing when a hereditary form is suspected. Treatment depends on the specific subtype and severity. For forms involving true aldosterone deficiency, mineralocorticoid replacement therapy with fludrocortisone is the mainstay of treatment, often supplemented with sodium chloride, particularly in infants. For pseudohypoaldosteronism, high-dose sodium supplementation may be required, and in some cases, treatment with potassium-lowering agents or thiazide diuretics is employed. With appropriate management, many patients can achieve good electrolyte control, though lifelong monitoring and treatment adjustments are typically necessary. Some milder forms may improve with age, particularly certain types of pseudohypoaldosteronism type 1.

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