Response to cabergoline treatment, gonadal axis recovery, and outcomes of drug withdrawal, in men with microprolactinoma: a retrospective cohort study.

Purpose: Due to the low incidence of male microprolactinoma, there is a paucity of data in the literature regarding its management. Our aim was to investigate the long-term outcomes of cabergoline treatment in men with microprolactinoma.

Methods: In this single-center retrospective cohort study, we reviewed patient's records at prolactinoma diagnosis, following cabergoline discontinuation (if occurred), and at the last clinic visit. We collected all available clinical data, laboratory tests, and pituitary magnetic resonance imaging. We report response rates, gonadal axis recovery, and outcomes following cabergoline discontinuation.

Results: The study cohort included 47 men with microprolactinoma [age at diagnosis 45.6 ± 17.6 years; median prolactin 70.0 ng/ml (IQR 51.0-103.4); low testosterone, 34 men (72.3%); adenoma diameter 5.6 ± 2.0 mm; median follow-up 7.1 years (IQR 3.5-10.4)]. Forty-two patients (89.4%) achieved normal prolactin levels within a median treatment time of 4.0 months (IQR 3.0-5.5) and had normal testosterone at last clinic visit. Five men (10.6%) did not achieve prolactin normalization, of whom 3 men remained hypogonadal. Mild side effects occurred in 4.3% of patients and disappeared with dose reduction. Thirteen men that achieved normal prolactin attempted drug discontinuation, but only 5 remained with normoprolactinemia. Men who maintained normal prolactin levels were treated longer with cabergoline [median treatment of 10 years (IQR 4.6-10.3) vs 2.0 years (IQR 1.5-3.2); p < 0.01].

Conclusions: Ninety percent of men harboring microprolactinoma achieved normoprolactinemia and subsequent testosterone normalization with cabergoline treatment. Men that discontinued cabergoline after prolonged prolactin suppression (>5 years) achieved sustained remission. These findings assist informed decision-making, between medical and surgical treatment.