THU577 Acth Dependent Cushing Syndrome Identification And Management Challenges

Disclosure: B.C. Barreto: None. S. Patrick: None. H. Oktaei: None. H.O. Steinberg: None. Endogenous Cushing Syndrome(CS) is rare with an incidence of 0.2-5.0 per million people per year. 70 to 80% of CS is ACTH dependent and subclassified into Cushing Disease, Ectopic ACTH Syndrome and Ectopic CRH Syndrome. Ectopic ACTH secretion(EAS) has a variable clinical presentation. Atypical features like refractory hypokalemia in a patient with a tumoral lesion should raise suspicion. When imaging is inconclusive, differentiating between pituitary or ectopic disease includes invasive and noninvasive methods. We report a case of EAS. Case: A 57-year-old male with history of metastatic small-cell lung-cancer on palliative chemotherapy was admitted for acute coronary syndrome. Endocrinology evaluated the patient’s uncontrolled hypertension, hyperglycemia, and hypokalemia (1.5 mmol/L). He had no suppression with low dose dexamethasone (cortisol>75mcg/dL, ACTH 926pg/mL). Examination was pertinent for an elevated BMI 36.1kg/m2, hyperpigmented anterior thorax but no other stigmata of hypercortisolism. Laboratory analysis showed baseline cortisol 146.1mcg/dL(8.7-22), ACTH 590pg/ml(6-50), 24hr Urine Free Cortisol 736mcg/24h(5-50), which were not suppressed by high dose dexamethasone suppression test(HDDST). Aldosterone and PRA were undetectable. Brain MRI showed an enlarged pituitary gland, but no focal mass. CT abdomen pelvis showed bilateral adrenal hyperplasia, multiple hepatic masses, and bone lesions. Since the patient was a poor surgical candidate, medical therapy was initiated with ketoconazole 200mg TID, aldactone 50mg BID and potassium chloride 40mEq TID. After twelve days cortisol levels decrease to 65.2 mcg/dL, potassium 3.8 mmol/L and glucose 146 mg/dL. Hospitalization was complicated by a small bowel ileus. Medications were held due to poor gastrointestinal absorption and parenteral octreotide 200mcg TID was initiated. Once the ileus resolved, ketoconazole 200mg TID, eplerenone 50mg daily, and dexamethasone 0.5mg daily was started. Despite medical care, the patient eventually expired. Discussion: The HDDST can help distinguish pituitary from an ectopic ACTH overproduction. HDDST with >50% suppression, has been described with sensitivity-specificity of 60 to 100% for pituitary ACTH source. Symptomatic treatment of CS requires rapid normalization of hypercortisolism action. Surgery is the first line approach. When surgery is not an option, medical therapy should be considered. Adrenal steroidogenesis inhibitors, such as ketoconazole, are the first line due to rapid onset of action. Agents such as glucocorticoid receptor antagonists have limited availability in the inpatient setting. Somatostatin analogs and etomidate that inhibit 11-ßhydroxylase are potential options but require close monitoring. Severe hypercortisolism in the critically ill prompts the use of noninvasive evaluation tools and alternative medical approaches. Presentation Date: Thursday, June 15, 2023