SUN-LB34 A Case of BMAH With Aberrant Vasopressin Adrenal Receptors

We report on a 42 - year old woman was referred following an incidental finding of bilateral macronodular (nodules > 1cm) adrenal glands after a computed tomography scan for investigation of an unrelated urological problem. Clear features of Cushing’s syndrome were elicited on initial clincal evaluation and screening tests confirmed the diagnosis biochemically: midnight salivary cortisol 15.4nmol/L (0.2 - 3nmol/L), 24 hour urine free cortisol > 662.4nmol/L (8.3 - 118.7nmol/L per 24 hours) and an 8am serum cortisol measured 951nmol/L following 1mg dexamethasone suppression test (< 50nm/L). A serum adrenocorticotropic hormone (ACTH) measured 0.3pmol/L (1.6 - 13.9pmol/L) suggesting, in light of the CT findings, an adrenal source of the elevated cortisol. Screening for aberrant adrenal receptors to catecholamines, Gastric inhibitory peptide, ACTH, vasopressin and Gonadotropin releasing hormone was performed. A positive biochemical response to ACTH and vasopressin was noted as measured serum cortisol increased to 1600pmol/L (upper limit of the assay). Following a unilateral adrenalectomy, were pathological examination of the respected adrenal gland confirmed adrenal hyperplasia, the patient had both clinical and biochemical resolution of hypercortisolemia. 2 weeks following surgery her midnight salivary cortisol measured 2.1nmol/L (0.2 - 3nmol/L) and 24 hour urine free cortisol 218nmol/L (8.3 - 118.7nmol/L per 24 hours). Her 8am ACTH also increased to 2.9pmol/L (1.6 - 13.9pmol/L). Biochemical screening of her sister showed no evidence of Cushing’s syndrome. Bilateral macronodualr hyperplasia (BMAH) represents a rare cause of Cushing’s syndrome may be diagnosed incidentally and is often associated with an insidious onset. We use this case to highlight the complexities of provocative testing for aberrant adrenal receptors which occur with BMAH and the utilization of unilateral adrenalectomy to achieve clinical and biochemical remission of Cushing’s syndrome thus, removing the need for post - operative steroid replacement following bilateral adrenalectomy.