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

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 ...