A Practical Strategy for Primary Aldosteronism Subtyping: Leveraging the Unilateral Adrenal Vein Sampling Index When...

Adrenal vein sampling (AVS) is the standard procedure for identifying unilateral primary aldosteronism (uPA) in surgical candidates. However, many patients undergo nondiagnostic or partially successful AVS, which may preclude them from curative surgery. This study aimed to evaluate the diagnostic utility of the unilateral AVS index for identifying uPA.

In this multicenter, retrospective study, we enrolled PA patients who underwent at least unilateral selective AVS, regardless of adrenocorticotropic hormone (ACTH) stimulation. The diagnostic accuracy of the relative aldosterone secretion index (RASI), calculated as the aldosterone-to-cortisol ratio between the selective adrenal veins and inferior vena cava, was evaluated using postoperative biochemical cure of uPA as a gold standard reference.

Excluding 54 patients with uncertain subtype, 140 patients (100 uPA and 40 non-uPA) were finally included in the diagnostic analysis. The area under the receiver operating characteristic curve of RASI from the culprit and nonculprit side was 0.730 and 0.771 with non-ACTH stimulation, 0.850 and 0.749 with ACTH stimulation. The optimal cutoff was >2.61 or <0.96 with ACTH stimulation, and >0.91 or <0.35 with non-ACTH stimulation. The combination of RASI with unilateral adrenal lesions, defined as unilateral adrenal nodules ≥5 mm or adrenal hyperplasia (adrenal limb thickness >5 mm or body thickness >10 mm) with a normal contralateral adrenal on computed tomography, improved diagnostic efficacy (area under the receiver operating characteristic curve = 0.815 to 0.873).

Our findings establish the utility of unilateral RASI in identifying uPA and lateralizing the responsible side, especially when combined with unilateral adrenal lesions, irrespective of ACTH stimulation.