Endocrine Abstracts

Case: A 73 year old man was seen in eye clinic with 5 month history of visual problems. He was diagnosed with bilateral glaucoma and early Cataracts. His vision was not improving despite eye drops and new glasses thus cranial imaging was requested. He also complained of feeling off balance and tiredness. He denied headache or galactorrhoea. Examination: Bitemporal hemianopia (L>R). Investigations: CT head scan – Pituitary Macroadenoma 3.6×3.1×3.8 cm, with displacement of Infundibulum in optic chiasm. Prolactin of 114 655 mU/l (No evidence of macroprolactin), LH <1.0 U/l, FSH 1.1 U/l, Testosterone 0.9 nmol/l. TSH 2.39 (0.35–4.5 mU/l), FT₄ 11 (10–25 pmol/l), FT₃ 4.6 pmol/l (3.0–7.0 pmol/l), cortisol 469 nmol/l, ACTH 13 ng/l. He was subsequently referred to the endocrine clinic. A diagnosis of macroprolactinoma was made in April 2016 and he was commenced on cabergoline 0.5 mg twice weekly. Testosterone was not replaced as it was thought that it would improve with lowering of prolactin levels. Three months post treatment (July’16), he reported no significant change in energy levels or vision. Prolactin had improved to 829 mU/l. MRI Pituitary in Aug’16 showed no change in size of adenoma. Scans were discussed at the pituitary MDT in Aug’16 where it was felt that there might be two separate lesions – pituitary adenoma and possible meningioma. He was urgently referred to neurosurgeons and ophthalmologists but a week later (beginning of September 2016) he presented with progressive visual field and acuity loss with worsening headache. He was diagnosed to have pituitary apoplexy and underwent transsphenoidal debulking of pituitary tumour. Post-operatively he had a stormy course with CSF leak -requiring repair, meningitis and hydrocephalus requiring a VP shunt. He continues on cabergoline 0.5 mg twice weekly and not on any hormone replacement therapy. His latest prolactin is 244 mU/l and his vision has improved slightly.

Discussion points:

i) Pituitary apoplexy has rarely been reported in context of cabergoline therapy.

ii) Approach to patients with discordant response to DA agonists’ therapy.

iii) Pre-existing visual conditions can hamper the assessment of pituitary induced visual loss.