A prolactinoma is usually a noncancerous (benign) pituitary gland tumor that causes the body to produce too much of the milk-producing hormone prolactin. This can cause different symptoms in females and males, ranging from irregular menstrual periods in women to erectile dysfunction in men.
The pituitary gland is located in the brain. It produces hormones related to growth and reproduction, among others.
In addition to prolactin, it produces follicle-stimulating hormone (FSH) and luteinizing hormone (LH), In females, these are associated with stimulating the body to produce eggs and regulating the menstrual cycle. In males, pituitary hormones lead to testosterone release and stimulate sperm production.
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Types of Prolactinoma
Typically, prolactinomas come in two size categories—small and large. Most are less than three-eighths of an inch in diameter and are known as microprolactinomas. These are more likely to affect females. The larger macroprolactinomas are more than three-eighths of an inch in diameter and are less common. These tend to affect males.
The symptoms associated with this condition vary depending on sex. For people with a uterus and/or ovaries, signs of this condition include:
- Halting of menstruation that is not related to other causes such as period irregularities or menopause
- Reduced sexual interest
- Breast milk production in those who are not nursing or pregnant
- Infertility from impaired egg release
- Vision issues and changes
Meanwhile, people with testes who have very small prolactinomas are typically faced with symptoms such as:
- Erectile dysfunction (inability to achieve or maintain an erection sufficient for penetration)
- Reduced sexual interest
- Breast enlargement
- Fertility issues
- Reduced peripheral vision or other vision changes
With larger prolactinomas, you are more likely to have vision problems or headaches. The nerves related to your eyes can be pressed by the pituitary gland, which is right beneath these nerves.
Symptoms from these larger tumors may include:
- Droopy eyelids, double vision, areas of vision loss, and other vision changes
- Nasal issues related to drainage or trouble with sense of smell
- Nausea and vomiting
- Sinus issues
Pituitary tumors like prolactinoma don’t tend to be associated with inherited factors, but this can occur. These usually arise spontaneously for unknown reasons.
Of hormone-producing pituitary tumors, prolactinoma is the most common. Prolactinomas make prolactin, which is associated with milk production. In some cases, prolactinoma may be part of what’s known as multiple endocrine neoplasia type 1, associated with endocrine tumors.
Prolactinoma is more often seen in females than males. In most cases, those with prolactinoma are younger than age 40 but this tumor is only rarely seen in children.
Your healthcare provider would take your medical history, ask what medications and substances you have used, and record your symptoms. Your physician will then perform a physical exam. Tests that may be done include imaging and blood tests.
A pituitary tumor may be found by magnetic resonance imaging (MRI) or computed tomography (CT) scan, with MRI being more commonly used.
Hormone levels will be checked with a blood test. If prolactin is 150–200 nanograms per milliliter (ng/ml), you likely have a tumor that is secreting prolactin. Stress and even just inserting the needle can also raise prolactin levels slightly. To see whether the level is consistently high, the test will likely be done more than once.
It’s also possible that your prolactin levels are increased by a condition known as macroprolactinemia. With this, there’s an elevation of prolactin levels but no clinical symptoms because prolactin’s interaction with blood proteins renders it inactive.
Other blood tests include testosterone levels, thyroid function tests to look for an underactive thyroid (which can raise prolactin), and further tests of pituitary function.
Usually, treatment for prolactinoma involves taking medication that mimics dopamine (which carries messages between nerves and brain cells) known as dopamine agonists. For 80%–90% of people, such medication effectively reduces tumor size, as well as prolactin levels.
Typical dopamine agonists include:
- Dostinex (cabergoline): This medication is commonly dosed at 0.5 milligrams (mg) is long-lasting and usually only needs to be taken up to twice a week. This has the fewest side effects and is usually the first medication prescribed.
- Parlodel (bromocriptine): Those on this medication take a 2.5 mg tablet two or three times a day. This is an older medication and is more likely to cause side effects such as dizziness, nausea, and headache.
- Norprolac (quinagolide): The dose for this once-daily medication is gradually increased to 75 micrograms.
Within a few weeks of taking these medications, prolactin levels usually drop back to normal. With the levels reduced, menstrual cycles usually return again for females, often restoring fertility, as well as libido (sex drive).
Likewise, the medication often shrinks the tumor, alleviating issues related to its pressing on nerves of the eye. If these effects were present, you will likely find that your vision improves.
While medication works for most patients, about 5% may find they’re resistant to the drugs. Likewise, another 5% may be unable to take these due to side effects.
In some of these cases, surgical removal of the tumor may be an option. If surgery is ruled out, another possibility may be use of radiation therapy to target the tumor. In many cases, carefully directed radiation can hone in on the tumor while sparing healthy surrounding tissue.
Prolactinoma is a usually noncancerous tumor of the pituitary gland that secretes high amounts of the hormone prolactin. This can lead to symptoms such as the loss of menstruation, erectile dysfunction, breast enlargement and/or milk production, infertility, headache, and vision changes.
Prolactinoma tumors can be either large or small. The symptoms for each type differ and may also be different in females and males. Also, the small tumors tend to be more common in females and the larger ones in males.
Treatment usually involves the use of medications to mimic dopamine, which are effective in as many as 90% of people with the condition. But surgery or radiation therapy are also possibilities.
A Word From Verywell
Having a prolactinoma may bring with it myriad symptoms, from infertility to vision problems. Once the condition is diagnosed, it can usually be successfully treated with medication within just a few weeks. Only in rare instances is additional treatment needed, such as surgical removal or use of radiation.