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Hyperaldosteronism

Evaluation for hyperaldosteronism should be considered in patients presenting with hypertension and unprovoked hypokalemia. Hypersecretion of aldosterone accounts for less than 1 percent of hypertension cases. Primary hyperaldosteronism is usually caused by a solitary, unilateral, adrenal adenoma and accounts for 70 to 80 percent of all cases of hyperaldosteronism. Other causes include bilateral adrenal hyperplasia, so-called idiopathic hyperaldosteronism, and glucocorticoid-remediable hyperaldosteronism. Adrenal carcinoma and unilateral adrenal hyperplasia are rare causes.

Clinical Presentation. Patients with hyperaldosteronism present with hypertension and hypokalemia. Other complaints include headache, muscular weakness, or flaccid paralysis caused by hypokalemia and polyuria.

Aldosterone levels can be measured in one of two ways: plasma aldosterone and renin testing or a 24-hour urine collection. Plasma aldosterone and renin are usually measured after four hours of upright posture. A ratio of plasma aldosterone concentration-to-plasma renin activity that is greater than 20 to 25 is highly indicative of hyperaldosteronism.

In a hypertensive patient with hypokalemia, kaliuresis, or an elevated plasma aldosterone-renin ratio, the diagnosis of hyperaldosteronism is confirmed by demonstrating failure to suppress plasma aldosterone. After oral sodium loadings normal.

Treatment. For adrenal adenoma, total unilateral adrenalectomy is the treatment of choice and provides a cure.

Although some patients with primary bilateral hyperplasia may benefit from subtotal adrenalectomy, these patients cannot be accurately identified preoperatively. After surgery, electrolyte imbalances usually correct rapidly, but controlling blood pressure may take precedence.

Medical therapy is indicated for most patients with bilateral adrenal hyperplasia and for patients with adrenal adenomas who are unable to undergo adrenalectomy. Spironolactone (Aldactone) may be used to control hyperkalemia, but is not a very potent antihypertensive agent. Amiloride and calcium channel blockers are often used.