Endocrine Abstracts

A 39-year-old man presented with thyrotoxicosis and was diagnosed with Graves’ disease. Despite high doses of anti-thyroid medication for 18 months, he remained biochemically and clinically hyperthyroid. Therefore, a thyroidectomy was planned. Four days before surgery, he developed double vision and was referred for urgent Neurosurgical review at our centre. On further questioning, he reported a 12-month history of lethargy and low libido. On examination, he had right 6th cranial nerve palsy and a partial right ptosis. A pituitary MRI showed a large suprasellar lesion with right cavernous sinus involvement. Biochemistry showed prolactin 37 384 mU/l (macroprolactin negative), testosterone 1.6 nmol/l, LH 1.5 IU/l, FSH 1.7 IU/l, T4 16.4 nmol/l, T3 7.2 nmol/l, TSH <0.01 mU/l, cortisol 53 nmol/l and IGF-1 23.2 nmol/l (13–50 nmol/l). His case was discussed at the ICHNT Pituitary MDT meeting. His thyroidectomy was cancelled and he commenced cabergoline 0.5 mg/week and hydrocortisone replacement. Serum prolactin fell quickly to 5456 mU/l after one dose of cabergoline 0.5 mg. Both the right-sided ptosis and 6th nerve palsy resolved.

With regards to his thyroid dysfunction, TSH receptor antibody level was raised at 2.1 u/ml (ULN 0.3) with a persistently elevated fT3 and undetectable TSH. He elected for radioactive iodine treatment rather than thyroidectomy as a definitive cure for his Graves’ disease. Nine weeks following radioactive iodine, he commenced thyroxine replacement (fT4 9.3 nmol/l).

A subsequent pituitary MRI showed a significant reduction in the size of the prolactinoma, albeit with persistent right parasellar extension to the cavernous sinus. Prolactin reached a nadir of 437 mU/l. However, he demonstrated low mood, with aggression and anger at out-patient review. After multiple discussions, he proceeded with a trial without cabergoline. Nine months later, his prolactin is static at 2494 mU/l and his mood improved. An interval pituitary MRI is being scheduled.

Questions for discussion: What are the options for this gentleman if his prolactin rises without dopamine agonists? Will surgery alone be sufficient in view of probable cavernous sinus involvement?