Hyperprolactinemia and Prolactinoma

Prolactin is released from lactotroph cells in the anterior pituitary. Hypothalamic dopamine normally restrains prolactin production and lactotroph growth through D2 receptors. A prolactinoma is a pituitary adenoma that secretes prolactin. Hyperprolactinemia is a laboratory finding with several possible causes; it is not, by itself, proof of a prolactinoma. Excess prolactin suppresses gonadotropin-releasing hormone. Luteinizing hormone and follicle-stimulating hormone then fall, reducing ovarian or testicular sex-hormone production. The resulting hypogonadism explains menstrual irregularity or amenorrhea, infertility, reduced libido, erectile dysfunction and reduced bone density or fracture risk over time. Galactorrhea may occur but is not required for the diagnosis. A pituitary mass can also cause symptoms independently of hormone excess. Upward extension can compress the optic chiasm and impair peripheral visual fields. Headache, reduced visual acuity, visual-field loss, diplopia or ocular palsy suggests local mass effect. Abrupt severe headache, acute visual change, vomiting, ocular palsy or reduced consciousness raises concern for pituitary apoplexy, an acute hemorrhage or infarction within the pituitary. Pregnancy, medication effects, primary hypothyroidism, renal insufficiency and liver failure can raise prolactin. A lesion that disrupts dopamine delivery...