Familial hypoaldosteronism

Familial hypoaldosteronism is a rare inherited disorder of adrenal steroid biosynthesis characterized by deficient production of aldosterone, the principal mineralocorticoid hormone responsible for regulating sodium and potassium balance in the body. The condition primarily affects the renin-angiotensin-aldosterone system and can be caused by defects in different enzymatic steps of aldosterone synthesis. Two main forms are recognized: type I, caused by mutations in the CYP11B2 gene (encoding aldosterone synthase, also known as corticosterone methyl oxidase), which can be further subdivided into corticosterone methyl oxidase type I (CMO I) and type II (CMO II) deficiencies; and other rarer forms. The disorder predominantly affects the kidneys' ability to retain sodium and excrete potassium, leading to electrolyte imbalances. Clinical features typically present in infancy or early childhood and include failure to thrive, dehydration, salt-wasting episodes, hyponatremia (low blood sodium), hyperkalemia (high blood potassium), and metabolic acidosis. In severe cases, particularly in neonates and infants, life-threatening salt-wasting crises with vomiting, poor feeding, and cardiovascular collapse may occur. Interestingly, the clinical severity often improves with age, and many affected adults may be relatively asymptomatic or only mildly affected, likely due to compensatory mechanisms for sodium retention that mature over time. Treatment focuses on correcting the mineralocorticoid deficiency and electrolyte imbalances. In infancy and early childhood, management typically includes sodium chloride supplementation and, in some cases, fludrocortisone (a synthetic mineralocorticoid). As patients grow older, the need for treatment often decreases, and some adults may not require ongoing therapy. Regular monitoring of serum electrolytes and growth parameters is important, particularly during childhood. Genetic counseling is recommended for affected families.

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