Our latest Clinical Practice article comes from Dr. Anne Klibanski of Massachusetts General Hospital and Harvard Medical School.
Prolactinomas are the most common type of secretory pituitary tumor. Typically benign, they are classified according to size; microadenomas are less than 10 mm in diameter, and macroadenomas 10 mm or more. Serum levels of prolactin in patients with prolactinomas are usually proportional to the tumor mass.
• What is the typical presentation of prolactinomas in women?
Clinical symptoms and signs of hyperprolactinemia in women include oligoamenorrhea, infertility, and galactorrhea. In women with hyperprolactinemia who continue to have menses, luteal-phase abnormalities can lead to infertility. Estrogen deficiency in amenorrheic women with untreated prolactinomas causes low bone mass, which is associated with an increased risk of fracture.
• What is the typical presentation of prolactinomas in men?
In men, hyperprolactinemia may lead to hypogonadism, decreased libido, erectile dysfunction, infertility, gynecomastia, and, in rare instances, galactorrhea. Decreased bone mass and anemia result from testosterone deficiency. In contrast with women, who usually present with microadenomas, most men present with macroadenomas, often with headache, visual symptoms, or both, in addition to hypogonadism.
Morning Report Questions
Q: Other than prolactinoma, what are other causes of hyperprolactinemia?
A: Secretion of prolactin is under tonic inhibitory control by hypothalamic dopamine; levels of prolactin can be increased in the presence of other tumor types, inflammatory disorders such as lymphocytic hypophysitis, cysts (e.g., Rathke’s cysts, which disrupt dopamine transport down the pituitary stalk), or medications that interfere with normal secretion of hypothalamic dopamine. These medications include antidepressants and antipsychotic agents (risperidone, in particular), other dopaminergic blockers (e.g., metoclopramide and sulpiride), some antihypertensive agents, opiates, and H2-receptor blockers.
Q: What treatment rapidly normalizes prolactin levels, restores reproductive function, reverses galactorrhea, and decreases tumor size in most patients with a prolactinoma?
A: Dopamine agonists are the primary therapy for both microadenomas that require treatment and macroprolactinomas. They rapidly normalize prolactin levels, restore reproductive function, reverse galactorrhea, and decrease tumor size in most patients. Dopamine agonists include bromocriptine and cabergoline (both ergot derivatives) and quinagolide (not approved for use in the United States).
Table 1. Indications for Therapy in Patients with Prolactinomas.