6917 Multiple Red Herrings Complicating the Diagnosis of Cyclic Cushing’s Syndrome

Abstract Disclosure: A. Grover: None. R. McGlotten: None. L.K. Nieman: None. Introduction: Cyclic Cushing’s syndrome (CCS) is a rare disorder characterized by intermittent hypercortisolemia. It may be caused by pituitary tumor (Cushing disease), ectopic ACTH tumor secretion (EAS), or primary adrenal disease. We present a case of CCS with multiple red herrings complicating the diagnosis. Case: A 57-year-old Cushingoid appearing woman presented elsewhere with weight gain, brain fog, weakness, hypertension, worsening diabetes, and OSA. Screening tests showed more than three episodes of hypercortisolism with interval eucortisolism: salivary and 24-urine cortisol (UFC) ranged from 0.06-0.34 µg/dL (reference range, RR, ≤0.09 µg/dL) and 59.7-137.1 µg/24 h (RR 4-50 µg/24 h) respectively. The patient was symptomatic throughout. Differential diagnosis was CCS vs a physiologic non-neoplastic condition. As she had no clear etiology for the latter, further testing was performed. ACTH was indeterminate (23-27 pg/mL, RR