Endocrine Abstracts

Ectopic adrenocorticotropic hormone (ACTH) production is a rare cause of Cushing’s syndrome. It is usually seen with small cell lung cancer, bronchial carcinoid, or medullary thyroid cancer. Rarely, the source of ectopic ACTH production can be a phaeochromocytoma. A 55 year old gentleman presented to a general physician following an episode of presumed gastroenteritis with vomiting and general malaise. Further episodes of diarrhoea, joint pains and palpitations followed. On examination, he was hypertensive with no obvious features to suggest any endocrinopathy. He was subsequently found to have raised plasma normetanephrines at 3.98 nmol/l (NR <0.71) and metanephrines at 0.69 nmol/l (NR <0.36). An adrenal CT showed a right 3.8 cm adrenal nodule which was subsequently found to be MIBG-avid in keeping with a diagnosis of phaeochromocytoma. He was started on alpha blockade and referred for right adrenalectomy. However, on admission for adrenalectomy, profound hypokalaemia was noted (potassium 2.0 mmol/l) with non-specific ST segment ECG changes. He was also found to have new onset diabetes (capillary blood glucose 28 mmol/l). He reported to have gained weight and his skin had become darker over the course of last four weeks. In view of these findings, he underwent overnight dexamethasone suppression test, which showed non-suppressed cortisol of 1099 nmol/l. Baseline ACTH was 273 ng/l. A preliminary diagnosis of ectopic ACTH secretion from the known right-sided phaeochrmocytoma was made and he was started on metyrapone. Surgery was postponed to the later date. This is a rare but interesting case of presumed ACTH secretion from a phaeochromocytoma presenting with weight gain, hypokalaemia and new onset diabetes. As phaeocromocytomas are adrenal medullary tumours, cortisol hypersecretion is not always routinely excluded preoperatively. However, this case emphasises the importance of investigations for hypercortisolaemia in known phaeocromocytomas in the appropriate clinical setting.