Hyperprolactinemia and Prolactinoma

Prolactin is produced by pituitary lactotroph cells. Unlike many pituitary hormones, prolactin secretion is held down continuously by hypothalamic dopamine acting at D2 receptors. Dopamine functions like a brake that is always engaged. When dopamine signaling is blocked, reduced, or interrupted, prolactin rises. Hyperprolactinemia means an elevated prolactin level. A prolactinoma is a prolactin-secreting pituitary adenoma, usually benign. The clinical consequences come from two directions: - Excess prolactin suppresses gonadotropin-releasing hormone, reducing estrogen or testosterone production. - A larger pituitary tumor can compress nearby structures, especially the optic chiasm. The hormonal pattern often includes menstrual irregularity, infertility, galactorrhea, reduced libido, erectile dysfunction, and symptoms of low estrogen or testosterone. A patient may also have headaches or visual changes from tumor mass effect. Galactorrhea supports the diagnosis but is not required; many patients with hyperprolactinemia do not have milk production. Tumor size changes the urgency. A small lesion may present through infertility or irregular menses. A macroadenoma may announce itself through a progressive headache, loss of peripheral vision, or cranial nerve symptoms. Sudden severe headache with an abrupt visual change is...