Gender differences in the prevalence, clinical features and response to cabergoline in hyperprolactinemia

Background: Gender differences in tumor size are supposed to exist in hyperprolactinemia since microadenomas are more commonly found in women and macroadenomas in men. Whether this reflects only a delay in diagnosis in men or a true gender difference in tumor pathogenesis is still unclear. Objective: To prospectively analyze gender differences in the presentation and response to cabergoline treatment in 219 consecutive newly diagnosed patients with hyperprolactinemia. Design: An open prospective design. Subjects: Of the 219 patients of which 145 were women: 107 patients had macroprolactinoma, 97 had microprolactinoma, and 15 had non-tumoral hyperprolactinemia. Methods: Presenting clinical symptoms, prolactin levels and tumor size at magnetic resonance imaging were measured before and 3-6 months after cabergoline therapy. Results: Prevalence of microprolactinomas (56% vs 22%, P =< 0.0001) and non-tumoral hyperprolactinemia (10% vs 0%, P = 0.01) was higher in women than in men. Men and women were of similar age (median 32 vs 29 years; P = 0.2) and a similar number had gonadal/sexual dysfunction (85 vs 83%, P = 0.6); weight gain (70 vs 46%; P < 0.0001) and galactorrhea (52 vs 19%; P =< 0.0001) were more common in women. Prolactin levels were higher in men than in women, whether exhibiting macro- (2848 ± 2954 vs 1132 ± 2351 μg/l, P =< 0.0001) or microadenomas (187.8 +/- 51.8 vs 135.4 +/- 60.5 mug/l, P = 0.009) and the size of the adenoma was larger in men than in women irrespective of macro- (25.8+/-12.4 vs 17.2 +/- 7.2 mm, P =< 0.0001) or microadenoma diagnosis (8.0 +/- 1.4 vs 7.1 +/- 1.6 turn, P = 0.04). After treatment, prolactin levels decreased by 89.2-96.4% in all groups, and normalized more frequently in micro- than in macroadenoma patients (86 vs 64%, P < 0.0001), regardless of gender (70% vs 69%, P = 0.9). Menses resumed in 82% of women, libido disturbances improved in 57% of men. Tumor size was reduced by 45 +/- 25% and 52 +/- 24% in macroprolactinoma patients and by 44 +/- 31 and 38 +/- 29% in microprolactinoma patients in women and men respectively. Visual field defects disappeared in 61% of women and in 71% of men (P = 0.6). Conclusions: Prevalence of macroprolactinomas was similar in men and women; microprolactinomas and non-tumoral hyperprolactinemia were more frequent in women. Clinical symptoms at presentation differed according to gender, with galactorrhea and weight gain more frequent in women. The successful response to cabergoline treatment for 6 months was higher in micro- than in macroprolactinoma patients and was similar in women and men.