Endocrine Abstracts

Background: Prolactinomas are the most common functioning pituitary tumours, accounting for 40% of all pituitary adenomas. Prolactinomas may enlarge in pregnancy, the management of which may prove challenging.

Case Presentation: A 23 year old lady was referred to the endocrine clinic with secondary amenorrhoea and bifrontal headaches in 2012. Biochemical tests on referral revealed: FT4- 5.8 pmol/l, TSH-1.1 mU/l, Prolactin-4432 mIU/l, LH- 4.8 IU/l, FSH- 4.6IU/l. CT head was suggestive of pituitary macroadenoma, with MRI (July 2012) confirming a cystic lesion in the pituitary (22x15 mm) with suprasellar extension, abutting the optic chiasm. Visual field testing was normal. She was commenced on cabergoline 250 mg twice weekly, which resulted in resolution of the adenoma and normalisation of serum prolactin levels (May 2013). A month later, she became pregnant and cabergoline was stopped. However, she had recurrence of headaches and self-reported left sided hemianopia. MR pituitary was hence repeated. This showed recurrence of pituitary macroadenoma measuring 14x12x14 mm protruding into the right sphenoid sinus. Repeat visual field was normal. She was re-started on cabergoline 250 mg twice weekly at 14 weeks of gestation. At 22 weeks of gestation, repeat MR pituitary showed further increase in size of the adenoma (16x13x15 mm), now abutting the optic chiasm. The dose of cabergoline was hence increased and an urgent neurosurgery advice was sought. As per neurosurgical advice, monthly MR scans and visual field testing were performed and no further increase in the size of the adenoma was noted. Following a normal full term delivery in 2014, she was continued on cabergoline. Serum prolactin again normalised (210 mIU/l) with resolution of the adenoma (August 2015). In 2016, she became pregnant again. Patient discontinued cabergoline and had recurrence of the pituitary macroadenoma (14x16x19 mm). Cabergoline was hence restarted and she was closely monitored with monthly visual field tests and MR scans. There was further enlargement of the adenoma (18x15x25 mm), displacing the optic chiasm superiorly at 33 weeks gestation. This was managed with increased dose of cabergoline in view of normal visual field assessments. Following delivery, her MR pituitary again showed shrinkage of the prolactinoma. She remains on cabergoline and under regular endocrine follow up.

Discussion: Pregnancy can cause recurrence of prolactinomas. Enlarging symptomatic prolactinomas are managed with dopamine agonists. Trans-sphenoidal surgery may be indicated in sight threatening macroprolactinomas, even in pregnancy.