What Are Pituitary Adenomas?
Pituitary adenomas are noncancerous tumors that grow in the pituitary gland, a pea-sized organ at the base of the brain that controls most of your body’s hormones. About 1 in 10 people have one of these tumors, but most never know it because they don’t cause symptoms. When they do, it’s usually because they’re either too big and press on nearby nerves or because they pump out too much of one hormone-most often prolactin.
Prolactinomas make up 40% to 60% of all pituitary adenomas. They’re the most common type that causes noticeable problems. When prolactin levels rise, it messes with your reproductive system, metabolism, and even your mood. In women, this often means missed periods, breast milk production when not pregnant, and trouble getting pregnant. In men, it leads to low sex drive, erectile dysfunction, and sometimes breast growth. Both sexes can feel tired, lose bone density, or develop headaches and vision issues if the tumor grows large enough.
How Prolactinomas Disrupt Hormone Balance
The pituitary gland normally releases just enough prolactin to support breastfeeding after childbirth. But when a prolactinoma forms, it starts overproducing the hormone-sometimes by hundreds or even thousands of times more than normal. Levels above 200 ng/mL usually mean a large tumor (called a macroadenoma), while levels under 100 ng/mL often point to a smaller one (microadenoma). A prolactin level over 150 ng/mL is almost always a prolactinoma, with 95% accuracy.
High prolactin doesn’t just affect reproduction. It shuts down the signals that tell your ovaries or testes to make estrogen and testosterone. That’s why fertility drops, libido vanishes, and bones weaken over time. If the tumor pushes against the optic nerve, you might lose side vision-something doctors check with a visual field test. And if the tumor grows big enough, it can block other pituitary hormones, leading to low cortisol, low thyroid hormone, or even diabetes insipidus.
Diagnosis: What Doctors Look For
Diagnosing a prolactinoma starts with a blood test. If prolactin is high, your doctor will rule out other causes like pregnancy, kidney disease, or certain medications (including some antidepressants and antipsychotics). Once those are ruled out, an MRI of the pituitary is the next step. A 3mm-thick scan is needed to spot even small tumors. For tumors larger than 1 cm, a visual field test is required to check for nerve damage.
Not all high prolactin levels mean a tumor. Sometimes a harmless, large clump of prolactin (called macroprolactin) shows up on blood tests and doesn’t need treatment. That’s why doctors don’t just treat based on one test-they look at symptoms, tumor size, and hormone levels together.
First-Line Treatment: Dopamine Agonists
For almost all prolactinomas, the first treatment isn’t surgery-it’s medication. Dopamine agonists like cabergoline and bromocriptine trick the tumor into stopping prolactin production. Cabergoline is now the gold standard. It works better, lasts longer, and causes fewer side effects than bromocriptine.
Doctors usually start with 0.25 mg of cabergoline twice a week. If prolactin doesn’t drop after a month, the dose goes up slowly-usually by 0.25 mg every two weeks-until levels normalize. Most people see prolactin drop within weeks. In 80-90% of small tumors, prolactin returns to normal in three months. Tumors shrink in 85% of cases. Even large tumors respond well: 70% see hormone levels normalize.
Many patients report feeling better within a month. Women get their periods back. Men regain libido. Headaches fade. But you can’t stop taking the medicine unless your doctor says so. Missing even a few doses can cause prolactin to spike again in as little as 72 hours.
Surgery: When Medication Isn’t Enough
Surgery isn’t the first choice-but it’s critical when medication doesn’t work or when vision is at risk. The standard procedure is transsphenoidal surgery: a surgeon goes through the nose to reach the pituitary. Endoscopic techniques (using a tiny camera) are now common and lead to faster recovery, less pain, and no visible scars.
Success depends heavily on tumor size. For microadenomas under 1 cm, surgery cures the problem in 85-90% of cases. For macroadenomas, it’s only 50-60%. Even when the tumor looks gone on MRI, prolactin can come back in 25-30% of large tumor cases within five years. Surgery also carries risks: 2-5% of patients get a spinal fluid leak, 5-10% develop temporary diabetes insipidus, and 1-2% experience pituitary apoplexy (a sudden bleed or loss of blood flow to the gland).
Many patients choose surgery if they can’t tolerate cabergoline’s side effects-like nausea, dizziness, or low blood pressure. Others opt for it if they want to get pregnant quickly and don’t want to wait months for medication to shrink the tumor.
Radiation Therapy: A Last Resort
Radiation is rarely used today because medication and surgery work so well. But it’s an option for tumors that keep growing after surgery or won’t respond to drugs. Two main types are used: Gamma Knife radiosurgery and conventional radiation.
Gamma Knife delivers a precise, high-dose beam in a single session. It controls tumor growth in 95% of cases after five years and rarely damages the optic nerve. But it takes years to lower prolactin-often 2 to 5 years. About half of patients still need hormone replacement after radiation because the treatment can kill healthy pituitary cells.
Traditional radiation (given over 5-6 weeks) has a higher risk of damaging the optic nerve and causing long-term hormone loss. That’s why Gamma Knife is now preferred when radiation is needed.
Long-Term Management and Monitoring
Prolactinoma isn’t usually cured-it’s managed. Even if prolactin normalizes and the tumor shrinks, you’ll need regular checkups. Blood tests every 3 months at first, then yearly if things stay stable. MRI scans every 1-2 years, especially if you’re off medication.
If you’re on cabergoline long-term (more than 2.5 mg per week for over 3 years), your doctor should check your heart valves with an echocardiogram. High doses can cause valve thickening in 2-7% of people. The FDA requires this monitoring for doses above 2 mg per day.
Some patients eventually stop medication after 2-5 years of normal hormone levels and no tumor on MRI. But only about 30% can stay off drugs without a relapse. For most, lifelong treatment is the reality.
What Patients Are Saying
On patient forums, stories vary. One woman with a 2.4 cm tumor saw her prolactin drop from 5,200 ng/mL to 18 ng/mL in six months on cabergoline. Her tumor shrank by 70%. She’s been on the same dose for three years and feels normal.
Another man switched from bromocriptine to cabergoline after severe nausea and dizziness made him quit. He says cabergoline “felt like a miracle”-no side effects, and his sex drive came back within weeks.
But surgery isn’t always smooth. One patient had a CSF leak after surgery and spent two weeks in the hospital. Another developed permanent low cortisol and now takes daily steroids.
Most agree: medication works fast, surgery is scary but effective for big tumors, and radiation is a slow, last-resort option.
What’s Next in Treatment?
Research is moving fast. A new drug called paltusotine, approved for acromegaly, is now being tested for prolactinomas. Early results show promise in lowering prolactin without the heart risks of cabergoline.
Scientists are also studying tumor genetics. Some prolactinomas have mutations in genes like GNAS or USP8 that make them more aggressive. In the next five years, doctors may use these markers to pick the best treatment for each person-instead of using a one-size-fits-all approach.
Other ideas include tiny drug-releasing stents placed inside the pituitary during surgery, or even CRISPR gene editing to fix faulty cells. But these are still years away.
For now, the best advice remains simple: get tested if you have unexplained infertility, low sex drive, or milk production outside of breastfeeding. Catch it early, and most prolactinomas can be controlled with a pill-no scalpel needed.
Can prolactinomas turn into cancer?
No, prolactinomas are almost always benign. They don’t spread like cancer or invade other organs. Even large tumors rarely become malignant. The real danger is how they affect hormone levels or press on nerves-not cancer risk.
Can I get pregnant if I have a prolactinoma?
Yes, but you’ll need treatment first. High prolactin stops ovulation. Once prolactin drops to normal with cabergoline, most women resume regular cycles and can conceive. Doctors often lower the dose during pregnancy, and many women stop medication entirely after confirming pregnancy. Regular monitoring is still needed.
Why is cabergoline preferred over bromocriptine?
Cabergoline works longer and stronger. You take it only twice a week, versus daily for bromocriptine. It normalizes prolactin in 80-90% of cases, compared to 70-80% for bromocriptine. Side effects like nausea and dizziness are also less common-about 20% with cabergoline versus 30-40% with bromocriptine. Most patients switch once they try it.
Do I need to take medication forever?
Not always, but most people do. About 30% of patients can stop medication after 2-5 years without the tumor coming back. But for the rest, prolactin rises quickly without treatment. Stopping without doctor approval can cause symptoms to return fast. Lifelong monitoring is standard, even if you’re off drugs.
What are the risks of long-term cabergoline use?
At high doses (over 2 mg per week for more than 3 years), cabergoline can cause thickening of heart valves, leading to regurgitation in 2-7% of patients. That’s why doctors recommend an echocardiogram after one year of high-dose treatment and every two years after that. At standard doses (under 2 mg/week), this risk is very low.