Primary aldosteronism: management issues

Since its initial description in 1955, primary aldosteronism was thought to be a rare cause of hypertension. However, improved screening methods show that primary aldosteronism is a common form of secondary hypertension. Diagnosis of this disorder results in improved or cured hypertension or targeted pharmacotherapy. Patients with hypertension and hypokalemia and most patients with treatment-resistant hypertension should undergo screening for primary aldosteronism. A random and ambulatory ratio of plasma aldosterone concentration (PAC) to plasma renin activity (PRA) that is elevated and a PAC higher than a set cutoff is a positive screen for primary aldosteronism. An increased PAC/PRA ratio alone is not diagnostic of primary aldosteronism; primary aldosteronism must be confirmed by demonstrating inappropriate aldosterone secretion with either the intravenous saline suppression test or measurement of 24-hr urinary aldosterone while the patient is on a high-sodium diet. The two major subtypes of primary aldosteronism are unilateral aldosterone-producing adenoma (APA) and bilateral idiopathic hyperplasia (IHA). Patients with APA are usually treated with unilateral adrenalectomy, and patients with IHA are treated medically. The subtype evaluation may require one or more tests, the first of which is imaging the adrenals with computerized tomography (CT). When a solitary unilateral macroadenoma (> 1 cm) and normal contralateral adrenal morphologic pattern are found on CT in a young patient with primary aldosteronism, unilateral laparoscopic adrenalectomy is a reasonable therapeutic option. However, in many cases, CT imaging may reveal normal-appearing adrenals or ambiguous findings. Adrenal venous sampling helps to resolve these clinical dilemmas.