A prolactinoma is a type of pituitary tumor (adenoma) that produces an excessive amount of the hormone prolactin. Prolactinomas are the most common type of hormonally-active pituitary tumor.
Symptoms of prolactinoma are due to abnormally high levels of prolactin in the blood (hyperprolactinemia), or due to pressure of the tumor on surrounding tissues. Based on size, a prolactinoma can be classified as a microprolactinoma (<10 mm diameter) or a macroprolactinoma (>10 mm diameter).
e symptoms due to a prolactinoma are broadly divided into those that are caused by increased prolactin levels or mass effect.
Those that are caused by increased prolactin levels are:
Amenorrhea (disappearance of ovulation periods)
Galactorrhea (Milk production; infrequent in men)
Loss of axillary and pubic hair
Hypogonadism (Reduced function of the gonads.)
Gynecomastia (an increase in male breast size)
Erectile dysfunction (in males)
Those that are caused by mass effect are:
Headaches
Vision Changes-visual field deficits, blurred vision, decreased visual acuity
Cranial nerve palsies-especially with invasive tumors or with pituitary apoplexy
Seizures, Hydrocephalus, Unilateral exophthalmos are rare presentations
Hypopituitarism
Pituitary apoplexy is a medical emergency because of spontaneous hemorrhage into the pituitary tumor and presents with severe headaches, vision changes, and acute panhypopituitarism.
Pregnancy
The pituitary enlarges and prolactin production increases during normal pregnancy in women without pituitary disorders. Women with prolactin-secreting tumors may experience further pituitary enlargement and must be closely monitored during pregnancy. However, damage to the pituitary or eye nerves occurs in less than one percent of pregnant women with prolactinoma. In women with large tumors, the risk of damage to the pituitary or eye nerves is greater, and some doctors consider it as high as 25%. If a woman has completed a successful pregnancy, the chances of her completing further successful pregnancies are extremely high.
A woman with a prolactinoma should discuss her plans to conceive with her physician, so she can be carefully evaluated prior to becoming pregnant. This evaluation will include a magnetic resonance imaging (MRI) scan to assess the size of the tumor and an eye examination with measurement of visual fields. As soon as a patient is pregnant, her doctor will usually advise that she stop taking bromocriptine or cabergoline, the common treatments for prolactinoma. Most endocrinologists see patients every two months throughout the pregnancy. The patient should consult her endocrinologist promptly if she develops symptoms — in particular, headaches, visual changes, nausea, vomiting, excessive thirst or urination, or extreme lethargy. Bromocriptine or cabergoline treatment may be renewed and additional treatment may be required if the patient develops symptoms from growth of the tumor during pregnancy.
At one time, oral contraceptives were thought to contribute to the development of prolactinomas. However, this is no longer thought to be true. Patients with prolactinoma treated with bromocriptine or cabergoline may also take oral contraceptives. Likewise, post-menopausal estrogen replacement is safe in patients with prolactinoma treated with medical therapy or surgery.
Learn more:
Managing Prolactinomas during Pregnancy