RADIATION-INDUCED HYPERPROLACTINAEMIA IN A TREATED ACROMEGALIC

Abstract

A 31 yr old acromegalic was normoprolactinemic after partial removal of her pituitary tumor. The post-operative external pituitary irradiation lowered the mean growth hormone (GH) level from 75 mU[units]/l to less than 1 mU/l within 2 yr. However, at the same time hyperprolactinemia developed. These changes in the GH and prolactin levels were confirmed 3 and 4 yr after irradiation. The cause of the hyperprolactinemia was radiation-induced hypothalamic damage. Similar damage may occur in patients receiving external pituitary irradiation for prolactinomas and this mechanism may contribute to the persistent hyperprolactinemia observed in such patients.