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  • Women: Oligomenorrhea, amenorrhea; galactorrhea; infertility.

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

  • Elevated serum PRL.

  • CT or MRI may show a pituitary adenoma.


Some causes of hyperprolactinemia are shown in Table 26–1. PRL-secreting pituitary tumors (prolactinomas) are the most common secretory pituitary tumor; they are usually sporadic but may rarely be familial as part of MEN type 1 or 4. Most are microadenomas (smaller than 1 cm), which are more common in women and typically do not grow even with pregnancy or oral contraceptives. Aggressive macroprolactinomas (larger than 1 cm) are more common in men and can spread into the cavernous sinuses and suprasellar areas; rarely, they may erode the floor of the sella to invade the paranasal sinuses. Hyperprolactinemia (without a pituitary adenoma) may also be familial. Augmentation or reduction mammoplasty, and mastectomy may stimulate PRL secretion.

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. Prolactinomas are pituitary neuroendocrine tumors whose diagnosis is often delayed in men, such that pituitary prolactinomas may grow and present with late manifestations of a pituitary macroprolactinoma (1 cm 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 (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 Chapter 10). Suppression of PRL secretion with dopamine agonists can reverse the cardiomyopathy.


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