SUN-486 New Moon: The Hidden Phase of Autonomous Cortisol Secretion From Bilateral Adrenal Adenomas

Abstract Disclosure: K.F. Mendoza: None. V.E. Bravo: None. D.L. Elazegui: None. G.D. Wassmer: None. Mild autonomous cortisol secretion (MACS) is an increasingly recognized entity in a substantial number of patients with adrenal adenomas. Unlike overt Cushing’s syndrome presenting with hallmark features such as moon facies, MACS remains silent yet clinically significant, contributing to an increased cardiometabolic risk and mortality. The best treatment strategy, particularly in cases of bilateral adrenal adenomas, is still debated. A 68-year-old male with a 5-year history of uncontrolled hypertension and diabetes presented with persistent headaches. These two conditions insidiously weaved together an amplified threat over the years, with a previous diagnosis of coronary artery disease, and now - an acute intraparenchymal hemorrhage in the right parietal lobe seen via cranial MRI on ED presentation. Amidst this already complex backdrop, bilateral adrenal nodules were also incidentally discovered on contrast enhanced abdominal CT scan (L: 11x13 mm, precontrast 15 HU, absolute washout 71.6% | R: 7x6 mm precontrast 20 HU, absolute washout 62.7%). Further work-up revealed low-normal ACTH (15.92 pg/mL) and unsuppressed cortisol (25.82 ug/dL) after an overnight dexamethasone suppression test. Adrenal venous sampling revealed cortisol hypersecretion in both adenomas with left predominance, exhibited by an AV/PV ratio of 5.6 and a lateralization index of 2.49.1 This hypercortisolemic environment continuously exposed the patient to unignorable risks, hence the need for timely intervention was compelling. There is still no established single treatment approach for MACS in bilateral adrenal adenomas. Various options have appeared in recent literature, each carrying its own risks and benefits. Based on the patient's age, comorbidities, and AVS findings identifying the side with dominant cortisol release, unilateral adrenalectomy was a favorable option to pursue to address his hypercortisolemic state with the least risk of adrenal insufficiency. This case of MACS from bilateral adrenal adenomas highlights the need to be clinically vigilant in evaluating subtle hypercortisolism, as its consequences can be severe. Subclinical autonomous hypercortisolism could be paralleled to a “new moon” - a phase that exists as a silent force of nature. In these cases, the absence of overt Cushingoid features still harbor a significant risk of morbidity and mortality and should not be ignored. In fact, addressing this “hidden phase” is crucial and warrants a cautious clinical eye to achieve a balance between prevention of cortisol-driven consequences and better patient outcomes. Reference:1.Johnson PC, Thompson SM, Adamo D, et al. Adrenal venous sampling for lateralization of cortisol hypersecretion in patients with bilateral adrenal masses. Clin Endocrinol (Oxf). 2023;98(2):177-189. doi:10.1111/cen.14833 Presentation: Sunday, July 13, 2025