Discordant responses of prolactinoma to two different dopamine agonists.
A 19-year-old woman presented with headaches, temporal lobe epilepsy and primary amenorrhoea. There was a family history of multiple endocrine adenomatosis. Investigation revealed normal visual fields and acuity, hyperprolactinaemia (48 000 mU/l) and a very large pituitary tumour with extrasellar spread. Treatment with bromocriptine reduced the tumour size and the prolactin level to 2440 mU/l. Six months after the start of therapy, resistance to bromocriptine developed and the prolactin concentration progressively rose to pretreatment levels, despite increasing the dose of bromocriptine to 40 mg/d. At this stage treatment with a second dopamine agonist, pergolide, was effective in reducing the prolactin concentration to normal within four months. Serial CT scans at 1, 6 and 12 months on dopamine agonist therapy showed a progressive decrease in tumour size, which seemed to be maintained even during the period of rising prolactin concentrations due to bromocriptine resistance. This case illustrates that during dopamine agonist therapy a discrepancy may exist in the clinical response as judged by reduction in tumour size and decrease in the circulating prolactin level. Furthermore, in patients with prolactinomas, pergolide may induce a response when resistance to bromocriptine develops.
D000328:Adult; D001971:Bromocriptine / Q000627:therapeutic use*; D004351:Drug Resistance; D004873:Ergolines / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D010479:Pergolide; D010911:Pituitary Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000378:metabolism; D011388:Prolactin / Q000378:metabolism*; D014057:Tomography, X-Ray Computed
D004873:Ergolines; D010479:Pergolide; D001971:Bromocriptine; D011388:Prolactin