Pathophysiology
Clinical meaning
Conn syndrome (primary hyperaldosteronism) is excessive aldosterone production independent of the renin-angiotensin system, most commonly from a unilateral aldosterone-producing adenoma (35%) or bilateral adrenal hyperplasia (60%). Aldosterone acts on the mineralocorticoid receptor in the principal cells of the collecting duct, upregulating ENaC (epithelial sodium channel) and Na+/K+-ATPase, causing sodium reabsorption with potassium and hydrogen ion secretion. This produces: hypertension (volume expansion from sodium retention), hypokalemia (potassium wasting), and metabolic alkalosis (hydrogen ion secretion). The elevated aldosterone suppresses renin (via negative feedback from volume expansion), creating the characteristic LOW renin, HIGH aldosterone pattern. Primary hyperaldosteronism is far more common than previously recognized, affecting 5-10% of all hypertensive patients and up to 20% of those with resistant hypertension.