Endocrine Abstracts

Introduction: Dopamine agonists have been routinely used in the treatment of prolactinomas since 1971. Increasingly, cabergoline is used as first-line treatment because of its tolerability and improved patient compliance. CSF rhinorrhoea is a rare but recognised adverse effect of rapid tumour shrinkage following dopamine agonist therapy. We report a case of cabergoline induced CSF rhinorrhoea in a young man with macroprolactinoma.

Case: A 26-year-old student presented with a 6 year history of bilateral spontaneous galactorrhoea and three months left visual field impairment. Initial investigation showed a markedly elevated serum prolactin of 215 000 μ/l and normal basal cortisol, IGF-1, testosterone, gonadotropin and thyroid hormone levels. MRI pituitary showed a large macroadenoma (5.5×3.6×3.1 cm) with downward extension in to sphenoidal sinus. Perimetry was essentially normal. He was commenced on cabergoline 0.25 mg thrice weekly increased after a week to 0.5 mg three times a week. Four weeks later he developed CSF rhinorrhoea and cabergoline was abruptly discontinued. Repeat MRI pituitary demonstrated considerable tumour shrinkage. He underwent surgical repair of CSF leak following which cabergoline was restarted. He has subsequently remained well without recurrence of CSF leak.

Conclusion: CSF rhinorrhoea following rapid tumour shrinkage after dopamine agonist therapy is rare and there is no consensus regarding patient management. Patients with large prolactinomas on dopamine agonist therapy should be warned of this potential problem and monitored closely.