Endocrine Abstracts

Introduction: Remission rate in microprolactinomas after treatment with dopamine agonists (DA) is variable, from about 25% in bromocriptine-treated patients to 46% in those treated with cabergoline.

Patients: We retrospectively studied the remission rate in 98 patients with prolactinomas ≤1 cm evaluated in 1982–2009 in our department and treated with DA for at least 1 year.

Results: Mean age of patients is 26.5±8 years, 99% were women. Defining resistance to DA as lack of serum prolactin (PRL) normalization after bromocriptine (BRC) ≥20 mg/day or cabergoline (CAB) ≥2 mg/week, 11 patients (11%) were resistant to DA (all to BRC, four also to CAB, one was responsive to CAB). Resistance to lower DA doses occurred in other 14 patients (14%), in 9 of them it was overcome by high DA doses. Normal prolactin was obtained after pituitary radiotherapy in two patients unequivocally resistant to DA.

In patients responsive to DA, the pituitary tumour decreased by ≥50% in only 16% of patients. Remission could be evaluated after DA withdrawal in 31 DA responsive patients, treated for median 3.9±4.7 years (range 1–21.6 years): four (13%) had normal PRL (normal pituitary imaging in one) at 1.2–3.8 years after DA withdrawal, other two had normal PRL at <6 months; six patients (20%) had equivocal remission: normal menses ± ovulation, with a mildly elevated PRL ± normal pituitary imaging (in one) at 0.5–6.6 years after DA withdrawal; 19 patients (61%) had recurrence of hyperprolactinaemia at median 3.5 months (0.5–5 years). The remission rate was not influenced by the type of DA, age, PRL or tumour size at diagnosis, or duration of treatment.

Conclusion: Dopamine agonists induced a long-term clinical remission only in 16% of patients with microprolactinomas (38% of DA – responsive patients) treated more than 1 year.