Primary Aldosteronism—One Picture Is Not Worth a Thousand Words

Physicians often rely on imaging to guide clinical decision making. When computed tomography (CT) or magnetic resonance imaging (MRI) is used to demonstrate adrenal morphologic appearance in patients with primary aldosteronism, the images may lead to errors in clinical management. In this issue, Kempers and colleagues (1) report a systematic review of the diagnostic procedures to distinguish between unilateral and bilateral adrenal disease in patients with primary aldosteronism. Their key finding, based on 950 patients with primary aldosteronism from 38 studies, is that the adrenal morphologic appearance on CT or MRI does not accurately identify the source of aldosterone excess (1).

Primary aldosteronism, first described by Conn in 1955 (2), is caused by renin-independent adrenal hypersecretion of aldosterone. Conn's first case was a 34-year-old woman with hypertension and hypokalemia caused by a unilateral adrenal aldosterone-producing adenoma. Hypertension and hypokalemia were cured with right adrenalectomy. In addition to aldosterone-producing adenomas, 6 other subtypes of primary aldosteronism were described over the subsequent 4 decades (3). Aldosterone-producing adenoma and bilateral idiopathic hyperaldosteronism are the 2 most common subtypes of primary aldosteronism—aldosterone-producing adenomas account for approximately 35% of cases, and bilateral idiopathic hyperaldosteronism accounts for approximately 60% of cases (3). In patients with an aldosterone-producing adenoma, unilateral adrenalectomy results in …