Mild hyperprolactinemia in clinical practice: the diagnostic “traps” and treatment strategy

Abstract

Real world clinical practice frequently poses the question on the advisability of diagnostic and/or treatment interventions for increased prolactin levels of below 2500 mU/mL (100 ng/mL), which is commonly considered as mild and not unequivocally indicating a prolactinoma. The aim of the review is to critically analyze the body of literature within the last 10 years on clinical and biochemical particulars of patients with mildly increased prolactin levels. We performed the search in Pubmed and RISC (Russian Index of Science Citation) databases with the keywords of “mild hyperprolactinemia” and “women” (or their Russian equivalents). After exclusion of the studies in patients with primary hypothyroidism or treatment with agents inducing prolactin secretion, as well as of clinical case descriptions, we selected 21 original papers with clinical and biochemical data of female patients with mild hyperprolactinemia (prolactin levels of less than 2500 mU/mL or less than 100 ng/mL). Symptoms of mild hyperprolactinemia include menstrual cycle disorders, anovulatory infertility and/or early pregnancy losses, breast disorders, psychoemotional and sexual disorders, and metabolic abnormalities. Repeated testing of prolactin levels to exclude potential stress related to the vein puncture allows for exclusion of 27% to 28% of the patients from further diagnostic work up. Confirmation of persistently increased prolactin levels warrants a magnetic resonance imaging study of the pituitary. Most patients with persistently increased prolactin levels by repeated tests would have pituitary abnormalities (in most cases, pituitary microadenoma). Taking into account the data on negative effects of even mildly increased prolactin levels on reproductive and metabolic health, it is reasonable to administer a first line agent cabergoline at doses ensuring normoprolactinemia. The results of studies indicate that treatment with cabergoline at doses necessary to normalize prolactin levels would lead to regression of menstrual dysfunction, decrease the probability of early pregnancy losses, improve metabolic parameters, promotes restoration of the sexual function, and diminishes the level of depression. This is especially important when planning pregnancy in patients with menstrual cycle disorders, infertility and/or early pregnancy losses.