Improving the Success and Reliability of Adrenal Venous Sampling: Focus on Intraprocedural Cortisol Measurement

Abstract

Primary aldosteronism (PA)2 is much more common than previously thought, possibly accounting for 5%–10% of hypertension cases (1, 2). Importantly, specific treatment of PA not only cures or improves the hypertension but also leads to amelioration of the excess cardiovascular damage and morbidity seen in these patients, compared with other forms of hypertension (1, 3). Consequently, recently published guidelines have recommended wider screening for PA via testing for the plasma aldosterone/renin ratio, in an effort to maximize the detection of patients who may then benefit from optimal, specific management (4). Once diagnosed, it is important to determine the subtype of PA, because the optimal treatment differs for each form. When PA is confined to a single adrenal gland (as in aldosterone-producing adenoma), unilateral adrenalectomy usually cures and virtually always improves the hypertension, with an accompanying improved quality of life. Bilateral forms, however, are more likely to respond to drugs—such as spironolactone, eplerenone, or amiloride—that antagonize aldosterone action. In most current series, unilateral forms make up approximately 30% of patients with PA, and bilateral forms make up the remaining 70% (2, 4). Computed tomography (CT) and other imaging modalities lack adequate sensitivity for identifying unilateral PA, because many aldosterone-producing adenomas are small (<1 cm) or the gland may only be mildly hyperplastic (2). Furthermore, CT may be frankly misleading by demonstrating unilateral nonfunctioning nodules in patients with bilateral PA or by showing nodules that are contralateral to the affected adrenal in unilateral PA (2). Owing to this diagnostic uncertainty, the only reliable way to differentiate unilateral from bilateral PA is by adrenal venous sampling (AVS), which seeks to estimate and evaluate each adrenal's aldosterone production separately (2, 4). The value of AVS is maximized when confounding factors that could complicate the interpretation of results …