MON-280 Adrenal Vein Sampling and Surgical Outcomes in Mild Autonomous Cortisol Secretion: A Case Series

Abstract Disclosure: M. Neff: None. J. Lin: None. J. Foster: None. N. Sharma: None. E. Garcia: None. J. Sandhu: None. E. Hilborn: None. S. Rodgers: None. A. Ayala: None. Z. Hannoush: None. Z. Miller: None. Introduction or Background: Mild autonomous cortisol secretion (MACS) is characterized by subtle hypercortisolism without overt Cushingoid features. The clinical significance and management of MACS remain controversial, particularly in patients with adrenal adenomas. Adrenal vein sampling (AVS) may aid in determining lateralization and guiding surgical decisions, but post-adrenalectomy (adrenalX) outcomes vary. Objectives: To present 2 cases of MACS evaluated by AVS, highlighting procedural outcomes, surgical outcomes, and post-adrenalX improvements. Methods: 2 patients diagnosed with MACS underwent AVS to assess cortisol secretion and guide adrenalX. Preoperative clinical, biochemical, and imaging data were reviewed. Post-op outcomes, including hypertension (HTN) control, BMI changes, and biochemical markers, were assessed at follow-up. Results: Case 1: 64yo male with bilateral adrenal adenomas (left: 1.8 cm, right: 1.3 cm and 1.1 cm). Dexamethasone suppression cortisol value was 5.7, and patient demonstrated no clinical features of overt Cushing’s syndrome. AVS indicated left-sided lateralization. Preoperatively, systolic BP was 154, diastolic BP 100 and BMI 31.1. Hypertension medications included amlodipine/benazepril 10-40mg, clonidine 0.1mg twice a day, and hydralazine 10mg 3 times a day. He underwent left adrenalectomy on 10/2022. Postoperative day 2, BP improved to systolic 141 and diastolic 96 but remained uncontrolled. Day 9 post-op, he experienced retroperitoneal hematoma in the adrenalectomy bed, anemia, and transient hypoglycemia, necessitating medication adjustments. 1-month post-op, BP was 136/88 without complaints or ongoing pain. By 5/2023, BP continued improving to 129/78, BMI decreased to 29.7 and medications included amlodipine/benazepril 10-40mg, hydralazine 50mg 3 times daily, and doxazosin 4mg. Case 2: 55yo male with a right adrenal nodule (1.0 × 0.6 cm). Dexamethasone suppression cortisol value was 2.5 with no Cushingoid features. AVS indicated right-sided lateralization. Preoperatively, systolic BP was 174, diastolic BP 95, and BMI 24.9. Pre-op hypertension medications included nifedipine 30mg, olmesartan 40mg, hydralazine 100mg in AM, 50mg in afternoon, and 50mg in PM, and labetolol 200mg twice daily. He underwent right adrenalectomy on 8/2024. At 2 months post-op, BP was well controlled on only nifedipine 30mg and doxazosin 4mg once daily. BMI decreased slightly to 24.3. Sodium, potassium, and renal function remained normal, and the patient reported significant clinical improvement. Conclusions: AVS guided adrenalX in MACS resulted in BP improvement and stable BMI, with varying degrees of antihypertensive reduction. AVS remains a promising tool for guiding surgical decisions in adrenal nodules with subclinical cortisol excess. With additional research the full potential of AVS in guiding adrenalX may be realized. Presentation: Monday, July 14, 2025