THU621 Mifepristone In Exogenous Cushing's Syndrome

Disclosure: S. Priyadarshan: None. D.O. Blavo: None. Introduction: Cushing’s syndrome is characterized by elevated cortisol levels in the body and is associated with significant morbidity and mortality. It can be broadly divided into endogenous and exogenous Cushing’s depending on etiology. Endogenous (body-produced) Cushing’s is diagnosed using Late Night Salivary Cortisol(LNSC), Dexamethasone Suppression Test(DST), or 24-hr Urinary-Free Cortisol(UFC) and after ruling out exogenous glucocorticoid administration. Hyperglycemia and weight gain are two of the many manifestations of Cushing’s that have hitherto proven to be a challenge to treat. Mifepristone is a glucocorticoid receptor antagonist that was recently FDA-approved for treating endogenous Cushing’s syndrome following the breakthrough SEISMIC trial. Literature regarding the utility of Mifepristone in exogenous Cushing’s has been limited since its approval. This case aims to fill that void. Case: A 35-year-old female with past medical history of rheumatoid arthritis was referred to endocrinology for further evaluation due to complaints of weight gain, dorso-cervical fat pad, abdominal striae, bruising of her right breast, and hirsutism requiring her to shave twice a week. She had previously been on prednisone 10mg-20mg daily for 2-3years for rheumatoid arthritis and was later weaned off due to her developing bruising, perioral abscess and dorsocervical fat pad. She was hospitalized for pneumonia later that year and discharged with dexamethasone. Her baseline weight at the time had been around 380lbs and she had a rapid weight gain over the next few weeks with a peak of 467lbs, associated with facial swelling and shortness of breath. For this, a DST was done per her primary provider among other labs and showed a cortisol level of 0.5mcg/dL(n<2mcg/dL). At the endocrine clinic, she had an extensive workup done including renin, aldosterone, plasma metanephrines, LH/FSH levels which all returned within normal limits. A1c was elevated at 6.7%(n <5.7%) and she was started on Metformin 1000mg BID. She had a repeat DST which suppressed cortisol appropriately however her midnight salivary cortisol was elevated. She was diagnosed with exogenous Cushing’s syndrome and started treatment with Mifepristone at 300mg daily. Her only side effect was mild nausea that later resolved. In 4 months, she had already lost 50lbs since her initial visit and HbA1c was down to 5.8. The dose was subsequently increased in increments up to 1200mg. In 7 months since starting Mifepristone, her weight was down to 312lbs, a total of 164lbs down from her initial weight. Her HbA1C was 4.6, down from her initial value of 6.7. Conclusion: This case is an excellent example of the effectiveness of Mifepristone in achieving glycemic control and weight reduction in Cushing’s syndrome with minimal side effects. More specifically, it serves to illustrate its utility in exogenous Cushing’s syndrome. Presentation: Thursday, June 15, 2023