PSAT024 A Case of Mild Autonomous Cortisol Secretion Managed with Active Surveillance

Mild autonomous cortisol secretion is characterized by the failure to suppress cortisol sufficiently after dexamethasone administration but without the stigmata of overt Cushing's syndrome. This condition, diagnosed in up to 50% of adrenal incidentalomas, has low overall rates of progression and mild cases can present a treatment dilemma. Here we describe one such case of cortisol excess well managed with a surveillance strategy rather than surgical intervention. A 49-year-old female with a past medical history of hypothyroidism was evaluated in the endocrine clinic for an incidental adrenal mass. CT imaging revealed a 2.7 cm left adrenal nodule, stable in size compared to prior imaging, with features typical of benign adrenocortical adenoma. Initial 1 mg DST with 8 am cortisol of 11.7µg/dl. Late night salivary cortisol (LNSC)level was found to be elevated at 130 ng/dl (nl<100 ng/dL). At that time, 24-hour urine free cortisol (UFC) was found to be borderline at 23.98 µg/day (nl<24 µg/day). Further testing at 6 months and 1 year from initial assessment showed persistently elevated LNSC level (110 ng/dL) and stable 24-hour UFC at 24 µg/day. Morning ACTH level was 19 pg/mL. One year after initial assessment, LNSC continued to be elevated at 0.106 µg/dL (nl <0.010–0.090 µg/dL) and repeat overnight 1 mg DST with 8am cortisol was unsuppressed at 10 mcg/dL representing at least two years of autonomous, mildly elevated cortisol levels. DHEA-S was low at 13.6 µg/dl (41.2 - 243.7 µg/dL). She had no history of diabetes, hypertension, obesity, hyperlipidemia or clinical osteoporosis. Her social history was negative for tobacco or alcohol abuse. Repeated physical exams were within normal limits, and she did not have any signs of central adiposity, abdominal striae, thinning of skin or hirsutism. She continued to deny any subjective symptoms of lethargy or muscle weakness. Given low normal range ACTH values, mildly increased midnight salivary cortisol, failure to suppress after 1 mg overnight DST with no clinical evidence of overt hypercortisolism, patient was diagnosed with mild autonomous cortisol secretion. She did not show any signs of hypertension, hyperglycemia or physical changes that would warrant concern for hypercortisolemic end organ effects. As the patient was largely asymptomatic, with stable CT imaging of left adrenal adenoma, left adrenalectomy was discussed but not recommended as patient preferred an observation surveillance strategy with laboratory evaluation every 6 months to monitor for hypercortisolemia. This case demonstrates that a surveillance strategy, rather than surgery, may be appropriate in selected cases of mild autonomous cortisol secretion from an incidentally discovered adrenocortical adenoma, especially when end organ effects of cortisol excess are clinically absent. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.