Abstract Disclosure: N. Zavrashvili: None. N. Margvelashvili: None. K. Chanturishvili: None. Mild Autonomous Cortisol Secretion in High Suspicious Adrenal IncidentalomaIntroduction: Incidentally discovered adrenal masses are common and mostly benign and non-functioning adenomas. However, evolving evidence suggests that a notable proportion of these adrenal adenomas may demonstrate mild autonomous cortisol secretion (MACS), which has been associated with an increased risk for hypertension, hyperglycemia, obesity, dyslipidemia, vertebral fractures, adverse cardiovascular events, and mortality. 55-year-old women with 5-year history of hypertension and hyperlipidemia. She was treated with a three-drug program: verapamil 250 mg daily, combined B-blocker, atenolol 100 mg and chlorthalidone 25 mg daily. Blood pressure control remained suboptimal. Her body mass index was 29,5 kg/m2. She had no signs or symptoms of overt Cushing syndrome.She was referred to CT coronary angiogram by her cardiologist, which revealed adrenal incidentaloma.Adrenal dedicated CT showed left-sided 3,4 cm high density node (41HU), with absolute washout <60. She was consulted by oncologist to exclude adrenal metastasis. The baseline laboratory test results excluded PA and Pheochromocytoma. The diagnosis of glucocorticoid secretory autonomy was based on positive low-dose dexamethasone suppression test (DST), low serum ACTH concentration, low-normal DHEA-S and lack of complete suppression of serum cortisol with an overnight 8-mg DST. Patient was referred to left-sided laparoscopic adrenalectomy with perioperative glucocorticoid coverage (100 mg hydrocortisone administered IV and again 8 hours later). Conclusion: Mild autonomous cortisol secretion is a term used to describe biochemical evidence of abnormal cortisol secretion in patients with adrenal incidentaloma, but without the classical external manifestations of overt CS, such as central muscle weakness, adipose tissue redistribution, and skin fragility. The management of patients with an incidentally discovered adrenal adenoma who do not have overt Cushing’s syndrome but who have MACS is more controversial as the available studies comparing outcomes of adrenalectomy vs conservative management have been generally small. It is associated with an increased risk of Type 2 diabetes mellitus, HBP, obesity, dyslipidemia, and global cardiovascular risk. Therefore, it is of great importance to correctly identify these patients. There are different tests for the screening of hypercortisolism. However, in the absence of a single test considered as the gold standard, it is necessary to combine the different tests to reach an adequate diagnostic capacity. The indication of surgery in ACS patients should be based mainly on the hormonal evaluation and the comorbidities potentially mediated by cortisol. Presentation: 6/1/2024