- Excessive secretion of Prolactin (PRL) can be caused by a variety etiologies; however, most cases are due to functional pituitary adenomas of lactotroph cells. In some cases non-lactotroph pituitary adenomas can cause hyperprolactinemia by compressing and blocking the hypothalamic-pituitary portal vessels, thus preventing hypothalamic dopamine inhibition of anterior pituitary PRL release (See: Prolactin Physiology).
- Women: Hyperprolactinemia often presents with galactorrhea (i.e. spontaneous, inappropriate lactation), infertility, and amenorrhea.
- Men: The signs of hyperprolactinemia are often more subtle and may manifest as decreased libido, impotence, or infertility. Because of the subtlety of clinical consequences in men, some patients may present with visual impairments associated with local mass effects of the growing pituitary adenoma.