People diagnosed with prolactinoma develop a benign tumor or adenoma on the pituitary gland in the brain, which leads to an overproduction of the hormone prolactin. The most noticeable effect of this is a decrease in testosterone levels in men and estrogen levels in women. Other symptoms include infertility and vision impairment. Depending on the size of the growth and severity of the condition, there are various treatments for prolactinoma, including medications, surgeries, radiation therapy, and chemotherapy.
Unfortunately, complete treatment of prolactinoma isn’t always possible, depending on the size of the tumor. When attempting to treat prolactinoma, physicians instead attempt to reach various goals:
The primary treatment method for prolactinoma is dopamine agonist medication. Dopamine is a chemical that directly inhibits prolactin secretion. Dopamine agonists force dopamine into action to shrink the adenoma and allow prolactin levels to return to normal. Doctors choose to use the most common of these medications because it is typically safe. However, some side effects can develop, such as nausea, dizziness, and nasal stuffiness. In minor cases of prolactinoma, dopamine agonists can correct the condition in a matter of days to weeks.
If patients react poorly to the most popular dopamine agonist, a second option is available. Most patients typically have a better tolerance to this variety, and it appears more effective at lower prolactin levels and restoring ovulation in women. Around 70 percent of patients who didn’t respond to the first treatment respond positively to the second. Unfortunately, because it is more effective, has fewer side effects, and is newer, the latter is significantly more expensive. This can act as a barrier for many patients who may not be able to afford the medication.
There are various reasons a physician may choose to perform surgery over using dopamine agonist medications. Primarily, surgery becomes an option for patients who cannot tolerate medications or when the medications fail to affect the tumor. The safest surgery for prolactinoma is a transsphenoidal pituitary adenomectomy. In this procedure, the surgeon attempts to remove the adenoma through the nasal cavity. Because the surgeon isn’t touching other areas of the brain, complication rates for this surgery remain low. Additionally, there is no visible scarring.
If the adenoma is particularly large or begins to spread to areas other than the pituitary gland, the patient may require a more serious procedure. In this instance, surgeons prefer transcranial surgery. The subfrontal approach is most common. Surgeons gently elevate the frontal lobes of the brain to create a path to the pituitary gland. They then remove the tumor from the surrounding brain and blood vessels. A major risk of this approach is damage to the frontal lobes, which can then lead to seizures, memory difficulties, or a loss of sense of smell.
For patients with small adenomas, surgery is an effective and fairly permanent treatment method. However, depending on the size of the tumor, prolactin levels, and skill of the surgeon, the patient may still require additional treatment. If prolactin levels were exceptionally high before the surgery, they are less likely to return to normal after the procedure. Typically, physicians prescribe drug therapy to assist patients who continue to experience elevated prolactin levels. This is most common when surgeons could only remove a portion of the affecting tumor.
Though it is uncommon, if a patient responds poorly to surgery and drug therapy, a physician may try radiation therapy. Over five or six weeks, doctors deliver radiation in low doses. Alternatively, some physicians choose to deliver a single, high dose of radiation. Only around 25 percent of patients experience a normalization of their prolactin levels following radiation therapy. In addition, complications can develop from radiation therapy, including seizures, optic nerve damage, and hypopituitarism.
One of the main difficulties of surgical procedures in treating prolactinoma is determining how much of the tumor was successfully removed. This occurs for various reasons, usually because membrane folds, arteries, or nerves obstruct a surgeon’s view. This can also affect radiation treatment as the level of radiation depends on the size of the remaining tumor. More advanced hospitals now use magnetic resonance operating rooms, which contain open MRI systems. This allows the surgeons to constantly receive high-resolution images of their patient’s brain.
Very rarely, medical experts may decide that chemotherapy is the most effective means to treat prolactinoma. Most choose to administer an oral chemotherapy alkylating agent that targets and damages DNA, thus triggering the death of tumor cells. The most common side effect of this drug is bone marrow suppression. This treatment can lead to a weaker immune system, less oxygen in the blood, and loss of blood clotting.
Because prolactinoma affects fertility, it can be difficult for women with the condition to become pregnant. However, some dopamine agonists may restore fertility. If a woman plans to become pregnant while undergoing treatment for prolactinoma, she should seek the advice of a medical expert. Her physician may need to tailor her treatment to her specific needs and desires. Often, a doctor will allow a pregnant woman to stop taking the drug, though she may need to resume treatment if prolactinoma symptoms develop.
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