Primary Medical Therapy of Micro- and Macroprolactinomas in Men*

The presentation and long-term therapeutic responses of PRL-secreting pituitary tumors in men have been only partially studied. Gender-specific differences in tumor size at clinical presentation and possible differences in tumor biology in men compared to women make it important to determine treatment outcomes of male patients with prolactinomas. We performed a retrospective review of men with prolactinomas medically managed at Massachusetts General Hospital between 1980 and 1997. We identified 46 male patients with prolactinomas managed with medical therapy alone. Twelve patients had microadenomas, defined as a serum PRL level greater than 15 ng/mL and a normal pituitary scan or a tumor smaller than 1 cm. Thirty-four patients had macroprolactinomas, defined by a serum PRL greater than 200 ng/mL and pituitary adenoma larger than 1 cm. Bromocriptine, quinagolide, and/or cabergoline were administered as medical therapy. All patients had at least one follow-up visit, and the most recent serum PRL measurement after initiating dopamine agonist therapy was reported. Baseline clinical characteristics for patients with macroprolactinomas and microprolactinomas showed a larger proportion of patients with macroprolactinomas reporting a history of headache (74% vs. 0%), whereas the prevalence of sexual dysfunction and testosterone deficiency was similar between the two groups. Median serum PRL at presentation was 99 ng/mL (range, 16-385 ng/mL) vs. 1,415 ng/mL (range, 387-67,900 ng/mL), in the microprolactinoma and macroprolactinoma groups, respectively. A normal PRL level was achieved in a similar percentage of men with microprolactinomas vs. macroprolactinomas (83% vs. 79%, respectively). Although the majority of patients in both groups were treated with bromocriptine, a comparable number of patients with microprolactinomas vs. macroprolactinomas achieved a normal PRL level with cabergoline therapy. The response rates for bromocriptine and cabergoline were similar in both groups. No patient with a microprolactinoma required hormone replacement therapy, in contrast to patients with macroprolactinomas, who required thyroid, testosterone, and/or glucocorticoid replacement therapy. No patient had evidence of an increase in tumor size during therapy. In summary, we investigated the clinical presentation and treatment outcome in men with prolactinomas. We found that normalization of serum PRL levels occurs in approximately 80% of men with prolactinomas. Of importance, dopamine agonist administration yielded similar biochemical remission rates in men with microprolactinomas and macroprolactinomas.