Endocrine Abstracts

History: A 62-year-old female presented with a 15-year history of tiredness and headaches. Clinically she had signs of acromegaly. This was confirmed with IGF1 688 ug/l and with a 2 h value (post GTT)of growth hormone 13.9 miu/l. MRI scan revealed a 3.5×3.5×2.5 cm mass in the pituitary fossa extending laterally to involve the left cavernous sinus and suprasellar extension causing moderate splaying of the optic chiasm. The left trigeminal nerve and internal carotid artery were also involved.

The patient was referred to the neurosurgeons who decided on hypophysectomy followed by radiotherapy and/or medication. Extensive residual tumour was left post-hypophysectomy due to extent and spread of tumour.

She was reviewed in clinic post-transphenoidal hypophysectomy for assessment regarding further treatment.It was noted she had a low T₄ 8.5 pmol/l pre-surgery, so baseline pituitary test were requested.

Her baseline prolactin was 53 642 mIU/l. Histology showed evidence of prolactin secreting cells, somatomammotrophinoma. She was commenced on 500 mg cabergoline, once a week, further titrated to twice a week.

Within one month her prolactin dropped to 14 000 mIU/l. Her cabergoline dose has been titrated subsequently, in an aim to normalise her prolactin. Future plan involves reassessing her tumour size and GH secretion once her prolactin level normalises.

Discussion: This case presents an interesting dilemma as this is a tumour secreting both GH and prolactin. Even though she is clinically acromegalic, it would be interesting to note the effect of the prolactin level, once normalised, on the initial tumour size. Initial surgery could not achieve cure due to the tumours’ size and extent, however, further surgery may be indicated if the tumour size shrinks appropriately. This may possibly help this patient to avoid radiotherapy and/or octreotide, which would be indicated if her prolactin levels were normal. It would also be interesting to observe the effect of dopamine agonists on the excess GH secretion.