FRI371 Serum Androstenedione As An Additive Biomarker In Ectopic Cushing’s Syndrome Evaluation

Abstract Disclosure: S. Zhang: None. J.C. Lo: None. M.G. Jaffe: None. H. Arzumanyan: None. Background: Ectopic Cushing’s syndrome (ECS) results from glucocorticoid excess secondary to ectopic ACTH or CRH producing tumors. Although ECS identification can be challenging when presentation lacks classic Cushing’s features, ectopic ACTH secretion can result in a key constellation of findings that facilitate early clinical recognition. We describe a case of ECS from an ACTH-producing carcinoid tumor of the lung presenting with resistant hypertension, severe hypokalemia, and muscle weakness. In addition to significant hypercortisolism, laboratory findings were notable for high androstenedione levels without concomitant increase in DHEAS and testosterone levels. Case: A 59-year-old female athlete with history of well-controlled hypertension developed difficult to control hypertension, requiring escalation to triple antihypertensive therapy within 3 months. During this time, she had multiple emergency department visits for progressive muscle weakness, hypertension, and persistent hypokalemia despite potassium supplementation. She was hospitalized for further evaluation. Physical examination was notable for bruising, muscle wasting, thin extremities, facial fullness, and disproportionate abdominal adiposity. Workup for Cushing’s syndrome demonstrated ACTH-dependent hypercortisolism and markedly elevated androstenedione 398 ng/dL (normal 20-75 ng/dL) despite normal DHEAS 48 mcg/dL (normal <430 mcg/dL) and total testosterone 11 ng/dL (normal <45 ng/dL) levels. A chest CT identified a 3.8 cm right lower lobe lung mass and transbronchial biopsy confirmed atypical carcinoid tumor. She underwent a right middle and lower lobe bilobectomy with complete tumor resection. Cortisol, androstenedione, and potassium levels rapidly normalized postoperatively, and blood pressure returned to baseline, well-controlled on monotherapy. The patient only required 3 days of hydrocortisone therapy for transient steroid withdrawal symptoms. Conclusions: Our case illustrates a difficult to diagnose uncommon disease presenting with resistant hypertension, hypokalemia and marked androstenedione elevation despite normal DHEAS and testosterone levels. This steroidogenic profile has been reported in other ECS cases and attributed to differential effects of ectopic ACTH production on adrenal androgen biosynthesis (1). Although ECS is rare and the primary lesion can be difficult to identify, disproportionate elevation in androstenedione may prompt recognition of ECS and support early detection and management. Reference: (1) Barbetta L, Dall’Asta C, Re T, Colombo P, Travaglini P, Ambrosi B. Androgen secretion in ectopic ACTH syndrome and in Cushing’s disease: modifications before and after surgery. Horm Metab Res Horm Stoffwechselforschung Horm Metab. 2001;33(10):596-601 Presentation: Friday, June 16, 2023