What is the most common cause of secondary hyperaldosteronism?

• A. Adrenal adenoma
• B. Renin-secreting tumors
• C. Secondary to Cushing syndrome
• D. Hypothyroidism

Answer: (B)

Secondary hyperaldosteronism is driven by activation of the renin-angiotensin system, so the key factor is elevated renin that stimulates aldosterone release. Among the options, the one describing a renin-secreting tumor directly raises renin levels, which in turn increases aldosterone production and produces secondary hyperaldosteronism. In contrast, an adrenal adenoma causes primary hyperaldosteronism, where aldosterone is produced autonomously and renin is suppressed. Cushing syndrome and hypothyroidism are not typical direct drivers of increased aldosterone via the renin–angiotensin pathway. Mechanistically, higher renin leads to more angiotensin II, which stimulates the adrenal cortex to secrete aldosterone, promoting sodium retention, potassium loss, and blood pressure rise. In clinical reality, common causes of secondary hyperaldosteronism are states of reduced renal perfusion (like renovascular disease or heart failure), but given these choices, the renin-secreting tumor best explains the increase in renin driving the condition.