MON-044 Not Just An Aldosterone Producing Adenoma

Abstract Disclosure: N. Patel: None. A.N. Mukhtar: None. P. Shooliz: None. 15% of adrenal adenomas are considered functional with most secreting one hormone. However, 14% of aldosterone producing adenomas (APAs) will co-secrete cortisol (Orrega & Chorny, 2020). In patients with APAs over the age of 35 without co-secretion, the next step is adrenal vein sampling (AVS). This case highlights the importance of recognizing APAs with co-secretion of cortisol without a completely suppressed Adrenocorticotropic hormone (ACTH) and the next steps in management. We present a 67 year old male with a history of hypertension and hypokalemia who presented with a left sided 3.3 centimeter (cm) adrenal nodule with non contrast attenuation of 29 Hounsfield units, 73% absolute washout value, and 55% relative washout value likely representing an adrenal adenoma. Laboratory testing supported APA diagnosis, with an elevated plasma aldosterone concentration (13.3ng/dl), suppressed renin (0.2ng/ml/hr), and increased 24 hour urine aldosterone excretion (28 μg/24 hours) with sodium of 212 mmol/24 hour. Testing for co-secretion of cortisol was confirmed by inappropriately high levels of cortisol at 5.3μg/dl after the dexamethasone suppression test. Patient’s morning ACTH levels were fluctuating from low-normal at 10 μg/dl to 27 μg/dl with normal serum cortisol level of 17.2 μg/dl. Given the above results, AVS was not completed and the patient underwent a left sided adrenalectomy with pathology revealing an 4.3cm adrenocortical adenoma. Postoperatively, after a few days, the patient became normotensive with resolution of hypokalemia. 1 week post operative aldosterone was 1 ng/dl, renin was 2.37 ng/ml/hr, and morning cortisol was 9 μg/dl. APAs greater than 2.4cm have a high probability of co-secretion of cortisol and a dexamethasone suppression test is recommended to rule out subclinical Cushing’s syndrome. Though our patient had varying levels of ACTH, with the larger size and low ACTH levels, as low as 10, pituitary cause was less likely. In APA with cortisol co-secretion, AVS is unnecessary due to 20% risk of misclassifying unilateral disease as bilateral adrenal hyperplasia (BAH), since cosyntropin infusion can falsely suppress lateralization. A patient diagnosed with BAH without co-secretion undergoes medical management rather than an adrenalectomy. However, in patients with an APA and co-secretion of cortisol that have BAH or a contralateral adrenal micronodule, the treatment is surgery to treat the hypercortisolism making AVS unnecessary. Patients with an APA that co-secretes cortisol require stress dose steroids intraoperatively followed by a taper to prevent a life threatening adrenal crisis. Overall this case illustrates the importance of diagnosing APAs that co-secrete cortisol as this leads to essential management changes. Presentation: Monday, July 14, 2025