Endocrine Abstracts

Microprolactinomas are the commonest pituitary tumour and respond well to dopamine agonist (DA) therapy with resolution of symptoms and tumour shrinkage occurring in the vast majority of cases. Reports also suggest that up to 20% of cases may achieve long-term normoprolactinaemic remission following withdrawal of chronic dopamine agonist therapy yet interruption of therapy is not universally practised nor is there consensus on the duration of therapy. In this retrospective study we have assessed normoprolactinaemic remission in a large cohort of treatment-naive subjects with microprolactinomas who had received 2 to 3 years of DA therapy prior to treatment withdrawal. Eighty-nine subjects ( mean age 32.7 +/- 8.4 yrs, 84 females and 5 males) received either Cabergoline (n=67) (0.5 - 3 mg weekly) or Bromocriptine (n=22) (2.5 - 10 mg daily) for a mean duration of 3.1yrs (range 0.33 - 10 yrs). Following withdrawal of therapy, recurrent hyperprolactinaemia was noted in 57 subjects (64%) and developed within a mean duration of 9.6 months (range 1- 44 months) whilst 32 subjects (36%) remained normoprolactinaemic beyond one year (mean 3.6 yrs, range 1-7 yrs). There was no difference in remission rates amongst subjects treated with Cabergoline (n=21) compared with Bromocriptine (n=11) but a direct relationship between pre-treatment prolactin concentration and risk of recurrent hyperprolactinaemia was observed. Seven subjects that had originally relapsed following therapeutic withdrawal, underwent a further cycle of treatment and withdrawal. One of these subjects (14%) treated originally with Bromocriptine, then with Cabergoline remained normoprolactinaemic for over one year. No one developed any adverse effects following therapeutic discontinuation nor was tumour expansion or DA resistance noted. In conclusion, this study confirms that withdrawal of chronic dopamine agonist therapy is safe and is associated with long-term normoprolactinaemic remission in 30-40% of treated subjects.