Endocrine Abstracts (2004) 7 P99

Factors determining remission of microprolactinomas after dopamine agonist withdrawal

JK Powrie & NB Athauda

Diabetes and Endocrine Department, Guy's and St Thomas' NHS Trust, London, UK.

It is common practice to attempt withdrawal of dopamine agonist (DA) therapy in patients with microprolactinomas who have achieved sustained normoprolactinaemia. There is, however little evidence to indicate which patients might attain long-term remission. The aim of this prospective study was to identify clinical factors that might predict such remission.

We recruited 40 patients (39 females and 1 male, age 24-60 years) with a diagnosis of microprolactinoma. Ethical approval obtained from the Trust Ethical Committee. All patients had been normoprolactinaemic on DA therapy for at least 2 years (mean 9, range 2-27 years). Patients planning conception or more than 60 years of age were excluded. An MRI scan was performed before discontinuation of therapy in 36 patients. Patients were reviewed 3 monthly for clinical and biochemical evidence of recurrent hyperprolactinaemia (prolactin more than 480 milliIU per litre on 2 occasions).

Nine out of 40 patients (22.5%) remained normoprolactinaemic after 9 months of treatment withdrawal. Remission and relapse groups were compared using student's t test and chi-square test or Fisher's exact test. Normalisation of the appearance of the pituitary on pre-withdrawal MRI scan occurred in 7 of 8 and in 5 of 28 patients in the remission and relapse groups respectively (p<0.001). Longer duration of DA therapy was also associated with remission (p<0.04). Age, pre-treatment prolactin, nadir prolactin and pregnancy while on treatment, history of previous relapse and type of DA used did not show any association with remission.

Resolution of the abnormality on MRI scanning may be an important predictor of long-term remission of microprolactinoma. A continued radiological abnormality within the pituitary may preclude successful DA withdrawal.

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