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Prolactin Response to Metformin in Cabergoline-Resistant Prolactinomas: A Pilot Study
Luiz Henrique Corrêa Portari1, Silvia Regina Correa-Silva1, Julio Abucham2
1Neuroendocrine Unit, Division of Endocrinology and Metabolism, Department of Medicine, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil.
Neuroendocrinology
|January 21, 2021
Summary
Adding metformin to cabergoline treatment did not significantly lower prolactin levels in patients with resistant prolactinomas. This combination therapy showed no consistent inhibitory effect on serum prolactin in this patient group.
Area of Science:
- Endocrinology
- Oncology
Background:
- Cabergoline is the primary treatment for prolactinomas, but 10-20% of cases exhibit resistance.
- Metformin, a diabetes drug, has demonstrated potential in reducing prolactin secretion in pituitary tumor cells.
- This study investigates metformin's efficacy in cabergoline-resistant prolactinomas.
Purpose of the Study:
- To evaluate the effect of adding metformin to cabergoline treatment on prolactin levels.
- To assess the efficacy of combination therapy in patients with resistant prolactinomas.
Main Methods:
- A prospective study involving ten adult patients with cabergoline-resistant prolactinomas and hyperprolactinemia.
- Patients received metformin (1.0-2.5 g/day) in addition to their existing cabergoline dosage.
- Serum prolactin levels were monitored at baseline, 30-60 days, and 120-180 days.
Main Results:
- No significant reduction in mean prolactin levels was observed after metformin addition (p = 0.196).
- None of the patients achieved normal prolactin levels during the study period.
- Only two patients showed a partial response (≥50% prolactin decrease) at a single time point.
Conclusions:
- Metformin addition to high-dose cabergoline treatment does not consistently inhibit prolactin levels in cabergoline-resistant prolactinomas.
- The combination therapy showed limited efficacy in managing persistent hyperprolactinemia in this resistant patient cohort.
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