Prolactinomas are the most frequent
pituitary adenomas. In patients with
prolactinomas the primary cause of
hyperprolactinemia is excessive and autonomic production of
prolactin by lactotroph cells. In other conditions, except in case of macroprolactinemia,
hyperprolactinemia is secondary to circumstances that stimulate secretion of
prolactin by intrinsically normal lactotroph cells, or, rarely, that are the result of decreased clearance of
prolactin. In general,
cabergoline is the preferred treatment for micro- and
macroprolactinomas, because it is more effective with respect to normalization of
prolactin levels and reduction of
prolactinoma size and because it has fewer side-effects compared to
bromocriptine. Recently, it has been suggested that a standardized, individualized, stepwise, dose-escalating regimen of
cabergoline may normalize
prolactin levels and reduce
prolactinoma size in patients who were otherwise considered to be
dopamine agonist resistant. In general, the cardiac adverse effects of
dopamine agonists reported in
Parkinson's disease are not of clinical concern in the treatment of
prolactinomas, which are treated with much lower doses. Nonetheless, there is uncertainty with respect to the dose and duration of
cabergoline treatment, which requires echocardiographic follow-up. Although withdrawal of
dopamine agonists may be considered in patients with
prolactinomas well controlled by
dopamine agonists, especially in postmenopausal women, recurrence of signs and symptoms may occur in a considerable portion of patients.