Prolactinomas are pituitary adenomas that secrete too much of the hormone prolactin (PRL). Prolactin normally is only secreted at a high level in women during pregnancy and during breastfeeding, as prolactin stimulates the breast to produce milk.
Excess prolactin from prolactinomas causes reduced reproductive function by inhibiting secretion of gonadotropin-releasing hormone (GnRH) by the hypothalamus. Normally GnRH stimulates the pituitary to produce luteinizing hormone (LH), which stimulates secretion of sex hormones, estrogen by the ovary and testosterone by the testes. Inhibition of GnRH secretion by high levels of prolactin results in reproductive-related symptoms.
Prolactin-secreting pituitary adenomas are the most common type of hormone secreting pituitary adenoma. Most prolactinomas occur in people under age 40, but are rare in children. Women are five times more likely than men to be diagnosed with a prolactinoma.
Symptoms of a Prolactinoma
As prolactinomas affect reproductive hormones, the symptoms are different for women and men.
Symptoms in women:
- Irregular periods or cessation of menstrual cycles
- Galactorrhea, production of milk by the breast (most common in women who are also taking oral contraceptives)
- Loss of sexual interest
- Osteoporosis (prolactin excess over time reduces the sex hormone estradiol)
Symptoms in men:
- Reduced sex drive or libido
- Erectile dysfunction
- Enlargement of the breasts, called gynecomastia
- Vision loss
Early diagnosis allows for tumors to be diagnosed when they are small, which improves the chance of cure following surgery alone.
Doctors can find a prolactinoma using either of these tests:
- Serum prolactin value (Elevated prolactin of greater than 150 ng/ml generally indicates the presence of a tumor)
Prolactinomas can be treated effectively by medical therapy and rarely require surgical treatment.
Early treatment prevents permanent effects, such as osteoporosis, caused by chronic prolactin overexposure.
The goals of treatment are to:
- Restore production of PRL to normal
- Stop and reverse the symptoms of prolactinomas
- Correct other endocrine abnormalities (thyroid, adrenal, ovaries or testes)
- Remove and/or destroy the tumor to restore endocrine function to normal and to relieve any symptoms directly related to the tumor (headaches, visual disturbance)
Dopamine agonist drugs mimic the effect of dopamine, which normally inhibits the secretion of prolactin. These oral medications include:
- Cabergoline (Dostinex)
- Bromocriptine (Parlodel)
Medication is taken on an indefinite basis and is effective in some 90 percent of prolactinomas.
Medication commonly results in shrinkage of the prolactinoma and after a few years of treatment some small prolactinomas may disappear.
Medication is required on an indefinite basis and the adenoma usually recurs if treatment is stopped. Regular follow up with measurement of prolactin and assessment of other pituitary function is required, together with MRI scans. If a recurrent tumor is found, additional treatment is necessary.
In women, medication usually results in restoration of menstrual cycles and pregnancy may occur. With larger tumors continued treatment is needed throughout the pregnancy but this is not required with smaller tumors.
Most prolactinomas respond to Dopamine agonsists, but some require surgical removal. This can be achieved by an transsphenoidal operation through the nose, which avoids the brain and eye.
After Successful Surgery
Once your prolactinoma is completely removed, the symptoms should resolve within days.
In larger tumors, usually in men, reproductive function may not return and additional treatment with replacement testosterone is required.
Radiotherapy is most often performed after surgery has removed the majority of a tumor that does not respond to medication, but some tumor remains that can’t be safely removed.
We use two main approaches at UVA:
- Gamma Knife radiosurgery
- External pituitary irradiation
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Content was created using EBSCO’s Health Library. Edits to original content made by Rector and Visitors of the University of Virginia. This information is not a substitute for professional medical advice.