SAT316 Severe Cushing’s Syndrome Due To Ectopic ACTH In Newly Diagnosed Small Cell Lung Cancer: The Pivotal Role Of Etomidate In Acute Treatment

Disclosure: H. Belal: None. G.Y. Gandhi: None. Introduction: Ectopic ACTH syndrome can present as an endocrine emergency. Etomidate, the only parenteral steroidogenesis inhibitor, can rapidly treat critically ill patients with Cushing’s syndrome (CS) and concurrent significant metabolic derangements, severe hypertension, or psychosis. Case Description: A 66-year-old female presented with abdominal pain, vomiting, proximal muscle weakness, and confusion for 6 months. Physical exam revealed hypertension, bilateral supraclavicular fat pads, and abdominal distention, while laboratory evaluation uncovered severe hypokalemia <1.5 mmol/L, metabolic alkalosis, and elevated proBNP. A hilar soft tissue mass with mediastinal lymphadenopathy and bilaterally enlarged adrenal glands were seen on CT imaging. Serum cortisol was high at 114 mcg/dL. ACTH was inappropriately elevated at 111 pg/mL. MRI revealed a normal pituitary gland. She developed hypertensive emergency and status epilepticus, requiring intubation. Due to her life-threatening presentation, a guideline-based hypercortisolism workup was forgone for emergent treatment with continuous etomidate infusion. Serum cortisol normalized after 4 days of etomidate therapy. Due to concerns of reduced seizure threshold with etomidate therapy, it was weaned off after 14 days and replaced by ketoconazole. She subsequently developed recurrent hypercortisolism (serum cortisol 92 mcg/dL). After 14 days of etomidate, 9 days of ketoconazole, and 3 days of chemotherapy for biopsy-proven small-cell lung carcinoma, serum cortisol reached a trough of 22 mcg/dL. At this point, hydrocortisone therapy was initiated (block-and-replace). Recurrent clinical hypercortisolism then developed, and hydrocortisone was discontinued. Hypercortisolism comorbidities were treated appropriately: trimethoprim-sulfamethoxazole for pneumocystis pneumonia prophylaxis, anticoagulation for DVT prophylaxis, antibiotics for acute diverticulitis, and insulin for hyperglycemia. Despite treatment, her condition worsened; she was transitioned to comfort care one month after admission and died 4 days later. Discussion: Etomidate inhibits steroidogenesis through 11 beta-hydroxylate blockade and works rapidly (within 12-24 hours) to decrease cortisol levels versus ketoconazole (several days) and has a reduced risk of hepatic injury. Side effects of etomidate include respiratory depression, myoclonus, and reduced seizure threshold. Several experts have suggested a block-and-replace strategy in severe CS treatment. While effective, this strategy poses risks of etomidate toxicity and makes serum cortisol interpretation unreliable. Etomidate analogs are on the horizon that retain the potent adrenostatic action of etomidate without its sedative-hypnotic activity, offering an alternative treatment option for treating patients with severe CS in non-ICU hospital settings. Presentation: Saturday, June 17, 2023