Endocrine Abstracts

A 69-year-old lady presented to the ophthalmologists in view of a right 6th cranial nerve palsy and headache. Neuroimaging showed a central and right sided base of skull tumour with involvement of multiple cranial nerves (3rd, 4th, 6th). An endoscopic biopsy was inconclusive. She presented to the medical team few days later with drowsiness, lethargy, and her sodium was found to be 117 mmol/l with a potassium of 5.5 mmol/l. Serum osmolality was 267 mOsm/kg, urine osmolality was 559 mOsm/kg and urinary sodium was 46 mmol/l. Thyroid function tests and cortisol levels were not done at this time. She was on amitriptyline, and the hyponatraemia was attributed to the drug, and this was stopped. She was managed as SIADH with fluid restriction, and thereafter her sodium improved to 125 mmol/l and she was discharged. She presented 48 hours later with reduced mobility. This time her random cortisol was 147nmol/l, with a low FT4 of 6.0 pmo/l, and low TSH of 0.06 mIU/l. Prolactin levels were normal. Her FSH was unusually low at 1.8 IU/l and her LH was < 0.2 IU/l despite her post-menopausal status. A clinical diagnosis of hypopituitarism was made and she was prescribed stress doses of oral steroids, but she had a cardiac arrest shortly thereafter probably secondary to the adrenal insufficiency, and was intubated. After improvement and stabilisation, she was kept on oral hydrocortisone for possible secondary adrenal insufficiency. Transnasal biopsy of the tumour done some weeks later suggested a lymphoma. MRI of the pituitary showed that the enhancing tumour was involving the cavernous sinus on the right and was inseparable from the pituitary gland, the stalk remained central and was not thickened. The pituitary gland was not enlarged. She is currently on chemotherapy which includes dexamethasone.