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  • Women: Oligomenorrhea, amenorrhea; galactorrhea; infertility.

  • Men: Hypogonadism; decreased libido and erectile dysfunction; infertility.

  • Elevated serum PRL; PRL is normally elevated during pregnancy.

  • CT or MRI may show a pituitary adenoma.


The causes of hyperprolactinemia are shown in Table 26–1. Augmentation or reduction mammoplasty, and mastectomy may stimulate PRL secretion. In acromegaly, there may be cosecretion of GH and PRL. Hyperprolactinemia (without a pituitary adenoma) may also be familial. PRL-secreting pituitary tumors are more common in women than in men and are usually sporadic but may rarely be familial as part of MEN type 1 or 4. Most are microadenomas (smaller than 1 cm in diameter) that do not grow even with pregnancy or oral contraceptives. However, some giant prolactinomas (over 3 cm in diameter) can spread into the cavernous sinuses and suprasellar areas; rarely, they may erode the floor of the sella to invade the paranasal sinuses.

Table 26–1.Causes of hyperprolactinemia.


A. Symptoms and Signs

Hyperprolactinemia may cause hypogonadotropic hypogonadism and reduced fertility. Men usually have diminished libido and erectile dysfunction that may not respond to testosterone replacement; gynecomastia sometimes occurs. The diagnosis of a prolactinoma is often delayed in men, such that pituitary adenomas may grow and present with late manifestations of a pituitary macroprolactinoma (diameter 10 mm or larger).

About 90% of premenopausal women with prolactinomas experience amenorrhea, oligomenorrhea, or infertility. Estrogen deficiency can cause decreased vaginal lubrication, irritability, anxiety, and depression. Galactorrhea (lactation in the absence of nursing) is common. During pregnancy, clinically significant enlargement of a microprolactinoma (diameter smaller than 10 mm) occurs in less than 3%; clinically significant enlargement of a macroprolactinoma occurs in about 30%.

Pituitary prolactinomas may cosecrete GH and cause acromegaly (see Acromegaly). Large tumors may cause headaches, visual symptoms, and pituitary insufficiency.

Aside from pituitary tumors, some women secrete an abnormal form of PRL that appears to cause peripartum cardiomyopathy (see ...

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