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For further information, see CMDT Part 26-04: Hyperprolactinemia

Key Features

Essentials of Diagnosis

  • Women

    • Oligomenorrhea, amenorrhea

    • Galactorrhea

    • Infertility

  • Men

    • Hypogonadism

    • Decreased libido and erectile dysfunction

    • Infertility

  • Elevated serum prolactin levels

  • CT or MRI may show pituitary adenoma

General Considerations

  • Table 26–1 lists causes of hyperprolactinemia

  • Augmentation or reduction mammoplasty, and mastectomy may stimulate PRL secretion

  • In acromegaly, there may be cosecretion of GH and PRL

  • Most are microadenomas (< 1 cm in diameter) that do not grow even with pregnancy or oral contraceptives

  • Some giant prolactinomas (> 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.

Demographics

  • Prolactin-secreting pituitary tumors more common in women

  • Usually sporadic but rarely familial as part of multiple endocrine neoplasia type 1 (MEN-1)

Clinical Findings

Symptoms and Signs

  • Hypogonadotropic hypogonadism

    • Men

      • Erectile dysfunction

      • Diminished libido

      • Gynecomastia (sometimes)

    • Women

      • Amenorrhea, oligomenorrhea, or infertility

      • Estrogen deficiency can cause decreased vaginal lubrication, irritability, anxiety, and depression

      • Galactorrhea

      • During pregnancy, clinically significant enlargement of a microprolactinoma (diameter < 10 mm) occurs in < 3%; clinically significant enlargement of a macroprolactinoma (diameter ≥ 10 mm) occurs in about 30%

  • Pituitary prolactinomas

    • May co-secrete growth hormone and cause acromegaly

    • Large tumors may cause

      • Headaches

      • Visual symptoms

      • Pituitary insufficiency (hypogonadism)

Differential Diagnosis

  • Increased pituitary size is a normal variant in young women

  • 10–25% of patients with hyperprolactinemia have macroprolactinemia, an increased circulating level of a high molecular weight PRL that is biologically inactive

  • See Table 26–1

Diagnosis

Laboratory Tests

  • The following tests should be done to rule out conditions that cause hyperprolactinemia:

    • Serum human chorionic gonadotropin (to rule out pregnancy)

    • Serum free thyroxine (FT4) and thyroid-stimulating hormone (TSH) (to rule out hypothyroidism)

    • Blood urea nitrogen and serum creatinine (to rule out kidney disease)

    • Liver biochemical tests (to rule out cirrhosis)

    • Serum calcium (to rule out hyperparathyroidism)

  • To evaluate men for hypogonadism, obtain

    • Serum total and free testosterone

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