About Open Access
Macroprolactinoma with progressive resistance to high-dose cabergoline
Lookup NU author(s)
Dr Chankramath Arun
Dr Stephen Ball
Dr Richard Quinton
Arun CS, Mitra D, Ball SG, Hill J, Lewis J, Quinton R
Conference Proceedings (inc. Abstract)
Endocrine Abstracts: 197th Meeting of the Society for Endocrinology
Year of Conference
6–7 November 2006
Full text for this publication is not currently held within this repository. Alternative links are provided below where available.
Introduction True resistance to cabergoline in patients with hyperprolactinaemia has only rarely been reported. We describe a patient with macroprolactinoma who initially responded to cabergoline, but then developed a progressive increase in PRL levels. Clinical case A 78-year-old male presenting with headache and left temporal hemianopia was found to have a macroprolactinoma with suprasellar/cavernous sinus extension and panhypopituitarism. The biochemistry dataset revealed central hypothyroidism dating back >5 years. On cabergoline 3.5 mg/wk, PRL fell progressively from 51,299 to 4,833 mU/L over a 7-month period with some tumour shrinkage. However, 14 months after initiation of medical therapy, PRL had risen again to 13,597 with evidence of tumour regrowth, despite a stepwise increase in cabergoline dose to 7 mg/wk. There was little response to octreotide challenge (12,998→8,466) and PRL rose further to 22,227 over the next month. Transsphenoidal surgery (TSS) was limited by severe vascular disease (circle of Willis fed by a single hypertrophic vertebral artery). Histology confirmed lactotroph adenoma with unusually high mitotic index. Post-op PRL was 13,597 and adjuvant fractionated multiportal EBRT was administered, resulting in a nadir PRL 17-months later of 1,665. However, despite cabergoline 10 mg/wk, there has since been tumour regrowth and further rise in PRL, peaking 3-years post TSS/EBRT at 19,606. Discussion It is unusual to develop resistance to cabergoline in patients who are initially sensitive. Due to physical frailty and tumour anatomy, he is not a candidate for further TSS or stereotaxic radiosurgery. Tablet non-adherence is a theoretical possibility, but following periods of supervised twice-weekly administration, we are confident this is not the case. Tachyphylaxis (documented in one previous case) is also a possibility and this could potentially be established by withholding cabergoline for 1–3 months and then rechallenging. Finally, tumour growth might be E2-driven, in which case a trial of aromatase inhibitor±stopping androgen replacement might be beneficial.
Search Newcastle University Library for this item
Newcastle University Library, NE2 4HQ, United Kingdom. Tel: 0044 (191) 222 7657
©2014 Newcastle University Library