THE EFFECT OF RALOXIFENE ON SERUM PROLACTIN LEVEL IN PATIENTS WITH PROLACTINOMA

To evaluate the effect of raloxifene on prolactin (PRL) levels in addition to dopamine agonist (DA) therapy in patients with prolactinoma. We conducted a retrospective chart review of 14 patients with prolactinoma on stable dose of DA for 6 months who received raloxifene 60 mg daily, as PRL could not be normalized despite being on fairly high doses of DA. Patients were informed that raloxifene is not approved by the Food and Drug Administration for prolactinoma treatment. PRL level was measured at 1 to 6 months after starting raloxifene and at 1 to 3 months following its discontinuation. Raloxifene was stopped in 8 out of 14 patients after 2 (1 to 6) months of treatment as the absolute change in PRL level was felt to be small. The median age and female/male sex ratios were 50 years (range 18 to 63 years), 6/8 respectively. The baseline DA dose was 3 mg/week (0.5 to 7 mg/week) for cabergoline and 15 mg/day for bromocriptine. Ten patients had an absolute and percentage decrease in PRL of 8.3 ng/mL (1.5 to 54.2 ng/mL) and 25.9% (8 to 55%) from baseline, respectively, after 1 to 6 months on raloxifene treatment. Among 10 patients with a decrease in PRL level, 2 (20%) achieved PRL normalization. Two patients had no change in PRL and two patients had an increase in PRL level by 22.8 ng/mL and 8.8 ng/mL (47% and 23.6%), respectively. Raloxifene was associated with a 25.9% (8 to 55%) decrease in PRL level in 10/14 (71%) patients with prolactinoma who were on stable doses of DA including 2 patients (14%) who achieved normoprolactinemia. Abbreviations: CV = coefficient of variation; DA = dopamine agonist; FSH = follicule-stimulating hormone; LH = luteinizing hormone; PRL = prolactin; PTTG = pituitary tumor transforming gene.