Prolactin disorders

Abstract

Hyperprolactinaemia can be physiological, pathological or drug induced. Elevated serum prolactin concentrations can cause secondary hypogonadism via inhibition of hypothalamic gonadotropin-releasing hormone and pituitary gonadotropins. Therefore, it is important to determine the pathological causes of hyperprolactinaemia, particularly prolactinoma. Female patients can present with galactorrhoea, menstrual irregularity and infertility, whereas male patients can present with symptoms of secondary hypogonadism. Notably, postmenopausal women and men often present with mass effects secondary to a large macroprolactinoma. Macroprolactin, representing <5% of circulating prolactin, is a polymeric form of prolactin with limited bioavailability and bioactivity. Macroprolactinaemia should be suspected in individuals with a raised prolactin concentration who lack typical features of hyperprolactinaemia. After confirming an elevated serum prolactin and excluding other physiological and pathological causes, pituitary magnetic resonance imaging should be performed to investigate the presence of a prolactinoma or non-prolactinoma pituitary tumour. Bromocriptine and cabergoline are the two dopamine agonists most commonly used to correct abnormal serum prolactin concentrations. Both cause tumour shrinkage in prolactinomas and restore gonadal function and fertility, but cabergoline is preferred as it is more effective and better tolerated. Although there are more safety data for bromocriptine than cabergoline, both are considered to be safe in pregnancy.