Endocrine Abstracts

A 52 year old man presented to his GP due to an increase in the size of his hands and feet. His wedding ring had become too tight and his shoe size had increased by three sizes. He had a change in his bowel habit but no headache or visual disturbance. Insulin-like growth factor-1 (IGF-1) was raised at 166 (9.8-26.3)nmol/l. He was referred to endocrinology. In clinic IGF-1 remained raised at 121 nmol/l, growth hormone (GH) was 40 ng/mL, and he was noted to have profound acromegalic features. Cortisol, TSH, T4, prolactin, LH, FSH, and testosterone were normal. MRI scan pituitary gland showed a macroadenoma with extension into the cavernous sinus, but no compression of the optic chiasm. He was diagnosed with acromegaly and referred for neurosurgery. He underwent transphenoidal resection of the pituitary adenoma. Post operatively he was started on hydrocortisone as per pituitary surgery protocol. His fluid input and output were monitored, with no evidence of AVP (arginine vasopressin) deficiency. Day 5 morning cortisol was 286 nmol/l. Daily steroids were stopped and he was discharged with steroids for sick days only. GH day 1 post operatively had reduced to 3.0 ng/ml. He re-presented two weeks later with dizziness, and was found to be hyponatremic at 126 mmol/l, with serum osmolality 272 (275-295)mOsm/kg, urine osmolality 183 mOsm/kg, and he was commenced on hydrocortisone daily. At follow up in endocrine clinic, he clinically felt well with no headaches, had some regression of his acromegalic features, and reduction in his blood pressure. His post-operative visual fields remained intact. Short synacthen test showed cortisol at T=0 at 311 nmol/l rising at T=30 to 523 nmol/l, following synthetic ACTH, and his daily steroids were stopped. Other pituitary blood tests remained in normal limits, and IGF1 now normalised to 33.5 nmol/l. Histopathology of his pituitary lesion was of somatotroph lineage, with no aggressive features, in keeping with a diagnosis of acromegaly. Repeat MRI pituitary scan did show an area of high signal reported as likely residual tumour. Oral glucose tolerance test found a growth hormone level of 2.8 ng/ml at 2 hours (<0.5 ng/ml) which was evidence of ongoing excess growth hormone secretion. He was discussed at a complex case meeting with the Neurosurgeon, with no further surgery planned at present. He will require ongoing monitoring of his biochemical markers for acromegaly recurrence, as well as screening for associated co-morbidities such as diabetes, hypertension, and obstructive sleep apnoea.