Endocrine Abstracts

Background: Withdrawal of dopamine agonist (DA) therapy in the management of microprolactinoma is common practice. It is unclear however which patients are likely to attain long term remission.

Aims: The aim of this prospective study was to identify clinical factors that might predict long term remission.

Subjects: Fourty subjects (39 female, aged 24–60 years) with microprolactinoma; all had been normoprolactinaemic on DA therapy for at least 2 years (mean duration of therapy 9 years (range 2–27)).

Intervention: An MRI pituitary scan was performed on 36 (90%) subjects before DA withdrawal.

Outcomes: Relapse of hyperprolactinaemia was defined as prolactin greater than 480 mIU/l (22.8 μg/l) on two occasions.

Results: Nine out of 40 (22.5%) subjects were normoprolactinaemic 12 months after withdrawal of DA therapy. Amongst the relapse group, 24 of 31 subjects (79.4%) had already relapsed at 3 months. The 9 subjects at remission at 6 months remained in remission at 1 year. Normalisation of MRI prior to DA withdrawal (P=0.0006) and longer duration of DA treatment (P=0.032) were significant predictors of remission. Age, pre-treatment prolactin, nadir prolactin, previous failure of DA withdrawal, pregnancy and type of DA were not significant predictors of remission. The 9 patients who were in remission at 12 months were then followed up for 58.0±5.8 months; all remained in remission.

Conclusions: Of 2.5% of subjects with microprolactinoma remained normoprolactinaemic 12 months after DA withdrawal and these subjects stayed in remission for up to five years. Significant predictive factors were normalisation of MRI prior to discontinuation, and duration of DA treatment. Our findings support intermittent DA withdrawal after a period of normoprolactinaemia, particularly where MRI appearances have normalised.