The outcome of 24 months of
cabergoline treatment on
prolactin (PRL) normalization,
tumor shrinkage, restoration of pituitary function, and semen alterations was prospectively investigated in 41 men with macro- (age 17-70 yr) and 10 with
microprolactinoma (age 18-53 yr). Fifty-one age-matched men served as controls for semen analysis. At study entry, of the 41 patients with
macroprolactinoma, 17 (41.4%) had visual field defects, 14 (34.1%) had
headache, eight (19.5%) had
galactorrhea, 22 (53.6%) had
hypopituitarism apart from
hypogonadism, and 30 (73.2%) had low
testosterone levels; of the 10 patients with
microprolactinoma, none had visual field defects,
galactorrhea, or
hypopituitarism apart from
hypogonadism, two had
headache (20%), and five had low
testosterone levels (50%; P = 0.3). After 24 months of
therapy, 1) PRL levels normalized in 31 patients with macro- (75.6%) and in eight with
microprolactinoma (80%; P = 0.9), and
galactorrhea disappeared in all patients; 2) maximal
tumor diameter reduced by 73.7 +/- 22.6% in macro- and 72.8 +/- 28.3% in
microprolactinomas (P = 0.91), and 15 macro- (30%) and seven
microprolactinomas (46.7%; P = 0.37) disappeared; 3) visual field defects disappeared in 15 (75%) patients with
macroprolactinoma, and
headache disappeared in 15 (83%) patients with macro- and in one with
microprolactinoma (50%); 4) GH secretion recovered in 62.5% and
ACTH secretion in 60% of patients; 5)
testosterone levels normalized in 25 patients with macro- (60.9%) and six with
microprolactinoma (60%) after 6 months, and 20 patients required
testosterone or
gonadotropin replacement (in 14 or six patients, respectively); and 6) sperm volume and count normalized in all patients who normalized
testosterone levels, whereas motility normalized in more than 80%.
Cabergoline therapy was well tolerated; only 4.5% of patients had side effects at high doses. These data demonstrate that
cabergoline treatment is as effective and safe in men as in women with
prolactinoma and can be successfully used as primary
therapy even in men bearing large
macroprolactinomas.