SAT-461 Adrenal Venous Sampling in Bilateral Adrenal Adenomas with ACTH Independent Autonomous Cortisol Secretion

Abstract Disclosure: A. Rothstein Costris: None. F. Manas: None. S. Athimulam: None. Introduction: Bilateral adrenal adenomas are found in up to 20% of patients with incidental adrenal nodules and often cause ACTH-independent mild autonomous cortisol secretion (MACS). While MACS patients may not exhibit obvious hypercortisolism symptoms, they can still experience metabolic, cardiovascular, and bone-related complications. Treating these adenomas is challenging; bilateral adrenalectomy is not recommended due to high morbidity and lifelong adrenal replacement needs. Medical treatments like steroidogenesis inhibitors or glucocorticoid receptor antagonists are still under investigation. Unilateral adrenalectomy is an option, but choosing which gland to remove lacks clear guidelines. Typically, the largest gland is removed, though it may not always be the primary source of excess cortisol. We present a case of bilateral adrenal nodules treated with adrenal venous sampling (AVS) and successful unilateral adrenalectomy, leading to symptom and biochemical improvement. Case Presentation: 56-year-old female with bilateral adrenal nodules (largest nodule 2.5cm on the right side, HU<10), resistant hypertension, obesity, osteopenia, and chronic kidney disease, presented with worsening symptoms of flushing, palpitation, facial swelling, weight gain, sweating, and tremors for the past 6 years. Prior work up was negative for catecholamine excess. She had abnormal cortisol levels post dexamethasone suppression test (DST). She had repeated DST multiple times and results were persistently elevated. 2 out of 3 late night salivary cortisol tests were abnormal. 24-hour urine cortisol was within normal range. Her ACTH and DHEAS levels were suppressed. She was diagnosed with ACTH-independent mild autonomous cortisol secretion. She underwent adrenal venous sampling (AVS) with dexamethasone suppression to evaluate for lateralization. The result of AVS was consistent with right adrenal gland dominance for cortisol production. She underwent partial right adrenalectomy to reduce the cortisol burden and improve excess cortisol related co-morbidities. In the post-operative period, she had an episode of hypotension and was started on hydrocortisone which was gradually tapered over 2 months. Her ACTH level improved from 3 pg/ml to 17 pg/ml (normal 7-63 pg/ml). Her blood pressure also improved, allowing her to reduce the number of medications from four to two. Discussion: Adrenal venous sampling is a minimally invasive test which helps determine if excess cortisol production is unilateral or bilateral, and decide further management in patients with bilateral adrenal adenomas with ACTH-independent mild autonomous cortisol secretion. When lateralization is confirmed on AVS, it can be treated with curative unilateral adrenalectomy leading to better outcomes for the patient. Transient adrenal insufficiency can be seen in patients due to suppressed ACTH after the surgery. Presentation: Saturday, July 12, 2025