Hyperprolactinemia in polycystic ovary syndrome

With the use of multiple blood sampling, the prevalence of hyperprolactinemia in 150 consecutive patients with polycystic ovary syndrome (PCO) was found to be 17%. To further compare these two groups of PCO patients, the pituitary responses to gonadotropin-releasing hormone and thyrotropin-releasing hormone and the adrenal responses to dexamethasone suppression and adrenocorticotropic hormone stimulation were evaluated in 40 normoprolactinemic and 10 hyperprolactinemic PCO patients. Adrenal and pituitary perturbation tests were normal in both groups of PCO patients. Besides the higher levels of prolactin, the hyperprolactinemic patients also had higher blood levels of thyrotropin and testosterone, a higher luteinizing hormone/follicle-stimulating hormone ratio, lower levels of follicle-stimulating hormone, and lower follicle-stimulating hormone responses to gonadotropin-releasing hormone. Our data are consistent with the hypothesis that in some cases, the pathogenesis of PCO may be due to a central deficiency in dopaminergic activity at the basal hypothalamus. The hyperprolactinemia observed in a significant number of PCO patients may reflect a greater deficiency of hypothalamic dopamine, as manifested by the basal elevations of both prolactin and thyrotropin levels.