Prolactin disorders

Abstract 

Hyperprolactinaemia can be physiological, pathological or drug-induced. Elevated prolactin can cause secondary hypogonadism via inhibition of gonadotrophin-releasing hormone and pituitary gonadotrophins. Therefore determining pathological causes of hyperprolactinaemia, particularly those due to a prolactinoma, is important. Female patients may present with galactorrhoea, menstrual irregularity and infertility, whereas men may present with symptoms of secondary hypogonadism. Macroprolactin is a polymeric form of prolactin, representing less than 5% of circulating prolactin and has limited bioavailability and bioactivity. In patients with a raised prolactin level who lack the typical features of hyperprolactinaemia, macroprolactinaemia should be suspected and screened for. Following confirmation of an elevated serum prolactin and exclusion of 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 most commonly used dopamine agonists to normalize serum prolactin concentrations, restoring gonadal function and fertility. These agents both cause tumour shrinkage in prolactinomas. Cabergoline is better tolerated than bromocriptine and this, in addition to its superior efficacy, makes it the dopamine agonist of choice in treating hyperprolactinaemia. Although there is more safety data for bromocriptine than cabergoline, both agents are considered to be safe in pregnancy.

Keywords: bromocriptine, cabergoline, dopamine agonist, hyperprolactinaemia, prolactin, prolactinoma