hypoaldosteronism

Hypoaldosteronism is a condition in which the body produces insufficient amounts of the mineralocorticoid hormone aldosterone or where aldosterone action is impaired. Aldosterone normally promotes sodium reabsorption and potassium excretion in the distal nephron; inadequate aldosterone disrupts fluid and electrolyte balance, typically causing hyperkalemia, hyponatremia, and volume depletion with low blood pressure in more severe cases.

Causes and classification

Primary hypoaldosteronism arises from adrenal cortex failure or destruction, such as Addison disease, where aldosterone production is low and renin levels are elevated. Secondary or hyporeninemic hypoaldosteronism results from reduced renin production, commonly in chronic kidney disease or diabetic nephropathy, where both renin and aldosterone can be inappropriately low or inappropriately normal. Less commonly, congenital or acquired disorders that directly affect mineralocorticoid synthesis or receptor function can produce a similar picture. Several medications that suppress the renin–angiotensin–aldosterone system or affect mineralocorticoid receptors may contribute to hyperkalemia and an apparent functional hypoaldosteronism.

Clinical presentation

Patients often have fatigue, weakness, dizziness, and salt cravings, especially with dehydration. Hyperkalemia can cause muscle weakness and cardiac arrhythmias; hyponatremia can contribute to confusion or hypotension. In primary forms, symptoms may reflect broader adrenal insufficiency, including fatigue and low cortisol.

Diagnosis

Laboratory assessment includes serum electrolytes (hyperkalemia, hyponatremia), bicarbonate (possible metabolic acidosis), and measurements of renin activity or concentration and aldosterone level to differentiate etiologies. The aldosterone-to-renin ratio helps distinguish primary from secondary causes in the appropriate context. Additional testing may include ACTH stimulation or cortisol measurement when adrenal insufficiency is suspected, and evaluation for underlying kidney disease or autoimmune adrenalitis.

Treatment

Acute management targets stabilization and hyperkalemia treatment as needed. Long-term therapy depends on the cause and may include mineralocorticoid replacement with fludrocortisone, dose titration based on potassium and sodium balance, and management of underlying disease. In Addison disease, glucocorticoid replacement is also required. Regular monitoring of electrolytes and blood pressure is advised.