Endocrine Abstracts

Case: We present the case of a previously fit and well 53-year-old lady who presented with persistent hypokalaemia (1.9 mmol). She was cushingoid and testing confirmed Cushing’s syndrome with random cortisol of >1750 nmol/l, ACTH 838 ng/l and non-suppressed cortisol (1099 nmol/l) after low dose dexamethasone suppression test. MRI pituitary was normal. Abdominal CT scan showed bilateral adrenal hyperplasia and large (>10 cm) mass with necrotic centre replacing the right lobe of the liver. Histology confirmed a high-grade metastatic neuroendocrine tumour. On octreotide scanning, this was intensely octreotide avid. Urinary 5HIAA (334 μg/ml) and chromogrannin A (>300 pmol/l) were markedly elevated. Her inpatient stay was complicated by type 1 respiratory failure, pulmonary oedema and pneumonia requiring ITU admission. Treatment options including hepatic resection and radiolabelled octreotide treatment were discussed extensively at the neuroendocrine MDT but she was unsuitable till her general condition improved. Despite treatment with metyrapone and then ketoconazole, her potassium remained low. She responded well to a trail of octreotide treatment (100 mg three times a day and then lanreotide 30 mg every 2 weeks). Cortisol decreased from >1750 to 156 nmol/l and ACTH from 838 ng/l to 115 pg/l after 3 weeks of treatment. She died a few months later with severe sepsis.

Discussion: Cushing’s syndrome due to ectopic ACTH secretion has a high morbidity and mortality, due to underlying tumour and the sequelae of severe hypercortisolemia. Rapid treatment is mandatory. Up to 80% of ectopic ACTH-producing tumours have somatostatin receptors suggesting somatostatin analogues (octreotide) may reduce ACTH production. However, the therapeutic role of these agents is still evolving. Our patient with ectopic ACTH secretion had a good biochemical response to octreotide. Octreotide is not a first line agent to control hypercortisolemia but may be a useful agent when other inhibitors of steroidogenesis fail or other options are not appropriate.