Unilateral Disease Is Common in Patients With Primary Aldosteronism Without Adrenal Nodules

Abstract

BackgroundPatients with primary aldosteronism (PA) without apparent adrenal nodularity have not been well characterised in the literature. The aim of this study was to assess for unilateral aldosterone hypersecretion among patients with primary aldosteronism with normal-appearing adrenals using adrenal vein sampling (AVS). MethodsIn this cross-sectional study performed at a Canadian tertiary care centre, we reviewed all consecutive PA patients lacking a definitive adrenal nodule who were referred for AVS in the work-up of PA between January 2006 and May 2018. AVS indications included an elevated aldosterone-to-renin ratio and high-probability features of PA. ResultsIn total, 174 patients were included (mean age, 52.0 years; 62.6% male), and 70 (40.2%) had unilateral aldosterone hypersecretion. There was a positive linear association between higher age categories (by decade) and lateralisation (P = 0.03). For every decade of age, there was a 30% higher odds of lateralisation (odds ratio, 1.03 per year; 95% confidence interval, 1.00-1.05). The frequency of lateralisation was higher in males compared with females (47.7% vs 27.7%), with a 2-fold greater odds of unilateral disease (odds ratio, 2.38; 95% confidence interval, 1.23-4.61). Traditional biomarkers of lateralisation among patients with adrenal nodules (eg, serum potassium and aldosterone-to-renin ratio levels) were not predictive of lateralisation in this population. ConclusionsMany patients with PA who lack definitive adrenal nodules have lateralising disease. Efforts to optimise referrals for AVS may be prioritised by focusing on patients most likely to have unilateral disease, especially males and older adults.