Abstract 94: Efficacy of cabergoline treatment in men with giant prolactinomas

Introduction: Giant prolactinomas in males are rare tumours in whom outcome data is scarce. Aims and Objectives: To evaluate the outcomes of therapy in men with ‘giant prolactinomas’ (>4 cm). Results: Of twenty-five males with macroprolactinoma following up in the Endocrinology Clinic; ten fulfilled the criteria of Giant Prolactinoma and were included in this retrospective study. The mean age was 34.2±12.67 years. Headache (n=10) and visual field defects (n=8) followed by hypogonadal symptoms (n=8) were the common presenting symptoms. A significant decrease of the Prolactin (PRL) values was observed in all patients (6420±1343.3 to 97.5±1.72 ng/dl; p= 0·0005). Persistent normalization of PRL levels was achieved in 7/10 patients. Significant tumour shrinkage (5±0.40 to 2.7±0.28 cm, p = 0·02) was achieved in 8/10 patients, with a volume reduction > 90% in three, >50% in four and >25% in one patient. Gonadotropin deficiency (n=9); TSH deficiency (n=4) and Cortisol deficiency (n=4) were uncovered on initial laboratory evaluation. The gonadotropin axis recovered in 1/9 and cortisol axis in 3/4 deficient subjects after normoprolactinaemia was achieved. The thyrotropin axis was affected irreversibly. Discussion and Conclusion: In male subjects with giant prolactinomas, recovery in other pituitary axes did not occur in spite of normalizing PRL levels and achieving tumour shrinkage.