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KembaraXtra- Medicine – Primary Aldosteronism (Hyperaldosteronism)
Primary aldosteronism is a group of disorders characterized by autonomous and excessive secretion of aldosterone, leading to renal sodium retention, suppression of plasma renin, and secondary hypertension. The condition classically presents with hypertension, hypokalemia, and metabolic alkalosis, although many patients may be normokalemic. Because aldosterone excess directly affects cardiovascular and renal systems, primary aldosteronism is now recognized as a common and clinically important cause of secondary hypertension.
Epidemiologic studies show that primary aldosteronism is far more prevalent than previously believed, particularly among patients with resistant hypertension. Current estimates suggest it may be present in 17% to nearly 27% of patients with resistant hypertension, with prevalence increasing as the severity of hypertension worsens. Familial forms of hyperaldosteronism are uncommon but should be suspected in patients with early-onset hypertension (before age 21), a family history of primary aldosteronism, or a family history of stroke before age 40.
The most common causes of primary aldosteronism include bilateral idiopathic adrenal hyperplasia, which accounts for approximately 60% to 70% of cases, and unilateral aldosterone-producing adenomas (Conn syndrome), which account for about 30% to 40%. Less common causes include unilateral adrenal hyperplasia, familial hyperaldosteronism, adrenal carcinoma, and ectopic aldosterone production. The underlying cause is important because it directly determines treatment strategy.
Clinically, many patients are asymptomatic aside from hypertension. When present, manifestations may include resistant hypertension, spontaneous or diuretic-induced hypokalemia, muscle weakness, fatigue, or a history of early cardiovascular events. A family history of early hypertension or stroke should heighten suspicion. Because symptoms may be subtle or absent, a high index of suspicion is required, particularly in patients whose blood pressure remains uncontrolled despite multiple antihypertensive agents.
Diagnosis begins with recognition of the biochemical pattern of suppressed plasma renin activity and elevated serum aldosterone levels, typically with aldosterone concentrations exceeding 15 ng/dL. Screening is recommended in patients with resistant hypertension, early-onset hypertension, hypokalemia, adrenal incidentalomas, sleep apnea, or a strong family history of hypertension or stroke. The aldosterone-to-renin ratio (ARR) is commonly used as an initial screening test, although its sensitivity is limited. When results are inconclusive, 24-hour urinary aldosterone excretion under aldosterone-suppressing conditions may be required for confirmation.
Routine laboratory findings are not diagnostic but may support the diagnosis, including hypokalemia, metabolic alkalosis, and occasionally mild hypernatremia. Once biochemical confirmation is obtained, imaging is performed to determine whether aldosterone excess is unilateral or bilateral. Adrenal CT scanning is the preferred imaging modality, as adrenal adenomas are typically lipid-rich and well visualized on CT. MRI may be used as an alternative. However, imaging alone cannot reliably distinguish unilateral from bilateral disease.
To definitively differentiate unilateral from bilateral aldosterone secretion, adrenal vein sampling (AVS) is recommended in most patients who are surgical candidates. This distinction is critical, as unilateral disease is best treated surgically, whereas bilateral disease requires medical therapy. AVS should be performed by experienced interventional radiologists to ensure accurate results.
Management includes both nonpharmacologic and pharmacologic strategies. Lifestyle measures such as regular blood pressure monitoring, a low-sodium diet, tobacco avoidance, weight management, and regular exercise are recommended for all patients. Acute management focuses on controlling hypertension and correcting hypokalemia, typically using mineralocorticoid receptor antagonists such as spironolactone or eplerenone, or potassium-sparing agents like amiloride.
Long-term medical therapy is the mainstay for patients with bilateral adrenal hyperplasia. Spironolactone is usually initiated at a low dose and titrated upward every two weeks to achieve a normal serum potassium level without supplementation. Eplerenone is an effective alternative with fewer antiandrogenic side effects, such as gynecomastia or menstrual irregularities. Amiloride may be used in patients who cannot tolerate mineralocorticoid receptor antagonists.
For patients with unilateral aldosterone-producing adenomas or unilateral adrenal hyperplasia, laparoscopic adrenalectomy is the treatment of choice. Surgical treatment typically resolves hypokalemia and improves blood pressure control, although hypertension persists in 40% to 65% of patients postoperatively. Complete resolution of hypertension is more likely in younger patients, those with a shorter duration of hypertension, fewer preoperative antihypertensive medications, no family history of hypertension, and higher aldosterone-to-renin ratios.
Overall, treatment of primary aldosteronism—whether surgical or medical—results in meaningful improvements in blood pressure control, potassium balance, and cardiovascular and renal outcomes. Untreated disease is associated with higher risks of stroke, myocardial infarction, atrial fibrillation, left ventricular hypertrophy, and decline in kidney function compared with essential hypertension. These risks are significantly reduced with appropriate therapy, and in many cases, surgical treatment lowers cardiovascular risk to below that of matched patients with essential hypertension.
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