Significance of aldosterone gradient within left adrenal vein in diagnosing unilateral subtype of primary aldosteronism.

Context: The success rate of cannulation of the right adrenal vein is limited. The aldosterone gradient within the same adrenal vein branch is specific for aldosterone‐producing adenoma. Objective: This study was performed to investigate whether the absolute aldosterone gradient within the left adrenal vein (left‐AV absolute aldosterone gradient) indicates unilateral excess aldosterone. Design and setting: A retrospective cross‐sectional study in a single referral centre. Patients and methods: In total, 123 consecutive patients with primary aldosteronism who had successful adrenal vein sampling (AVS) data were examined. The left‐AV absolute aldosterone gradient was considered significant when a gradient of >4:1 in the aldosterone‐to‐cortisol ratio between the common trunk vein and central vein was found. Main outcome measure: The prevalence of the unilateral subtype in patients with a significant left‐AV absolute aldosterone gradient. Results: The prevalence of the unilateral subtype was higher in patients with than without a significant left‐AV absolute aldosterone gradient (88.2% [15/17] vs 21.7% [23/106], P <.001). Of 60 patients with spontaneous hypokalemia, left unilateral disease on computed tomography, or both, a significant left‐AV absolute aldosterone gradient was present only in patients with the unilateral subtype on AVS (42.9% [15/35]), but not in those with the bilateral subtype (0.0% [0/25]). These data were validated in an external cohort. Conclusion: The presence of a significant left‐AV absolute aldosterone gradient can be used to diagnose the left unilateral subtype of primary aldosteronism on AVS in patients with spontaneous hypokalemia, left unilateral disease on computed tomography or both. [ABSTRACT FROM AUTHOR]