SUN-068 Adrenal Venous Sampling in ACTH-Independent Cushing’s: Evaluating Reference Hormones for Lateralization and Surgical Outcomes Following Adrenalectomy

Abstract Disclosure: M. Neff: None. J. Foster: None. J. Lin: None. N. Sharma: None. E. Garcia: None. J. Sandhu: None. E. Hilborn: None. S. Rodgers: None. Z. Hannoush: None. A. Ayala: None. Z. Miller: None. Background: The optimal laterality index (LI) for adrenal vein sampling (AVS) in evaluation of cortisol hypersecretion in Cushing’s patients remains undefined. The uncertainty is greater for patients with mild autonomous cortisol secretion (MACS). Some protocols use side-to-side cortisol lateralization ratio >2.3 to indicate unilateral dominant cortisol secretion (Young et al, Ueland et al), others use concordance of LI’s >2 from multiple reference hormones (Papakokkinou et al). Objective: This study evaluates the correlation between laterality interpretations using various reference hormones with imaging and post-adrenalectomy (adrenalX) clinical outcomes in patients with Cushing’s or MACS. Methods: A single center retrospective review was conducted on 11 patients with clinical and biochemical evidence of ACTH-independent Cushing’s or MACS who underwent AVS from 2021-2024. Blood samples from adrenal veins and IVC were analyzed for cortisol, aldosterone, epinephrine, and norepinephrine. Dominant lateralization was calculated using 2 methods: side-to-side cortisol ratio ≥2.3 and cortisol-to-aldo ratio of >2 . LI >2 was calculated for additional reference hormones and results compared with CT findings. Pre- and 3-month post-op BP and BMI were evaluated in adrenalX patients. Results: Among 11 patients, 2 had MACS. CT showed bilateral adenomas in 7, unilateral in 3, and none in 1. Dominant lateralization by either method was observed in 4/7 with bilateral and 2/3 with unilateral adenomas. Concordance between both laterality methods and all reference hormones was found in 1 patient with a unilateral nodule. 3 cases showed concordance between 1 method and at least 1 reference hormone and 3 showed no concordance. 4 patients underwent adrenalX. Median pre-AVS systolic BP144 (IQR: 129-152), diastolic BP 85 (IQR: 81-95), BMI 31.3 (IQR: 28.5-36.8). Post-AVS, SBP 129 (IQR: 112-129), DBP 78 (IQR: 75-78), and BMI 30.2 (IQR: 24.3-30.2). Of these 4, 1 had concordance across all methods, 2 had concordance between side-to-side cortisol and aldo, and 1 with aldo, epi, and norepi. All 4 patients experienced no complications and reported symptomatic improvement, including reduced fatigue, weight loss, and decreased need for antihypertensive medications. Conclusion: Post-adrenalX, patients with side-to-side lateralization showed clinical improvement and there was concordance of lateralization with at least one reference hormone in all cases. Cortisol-to-reference hormone ratios in AVS may enhance identification of unilateral cortisol hypersecretion in ACTH-independent Cushing’s and MACS. Concordance may be helpful in surgical decision-making in cases where imaging and biochemical assessments are incongruent. Presentation: Sunday, July 13, 2025