Medically Reviewed |
Last reviewed by
Jennifer Kaplan, M.D.,
Sarah B. Fisher, M.D., FACS and
Anna Lee, M.D., MPH
on
March 09, 2026
Multiple endocrine neoplasia (MEN) syndromes are rare genetic conditions that affect the endocrine system. People with MEN are more likely to develop tumors — either benign (non-cancerous) or malignant (cancerous) — in hormone-producing glands. In some cases, these glands become enlarged without forming tumors.
The endocrine system is made up of glands that release hormones into the bloodstream. These hormones control important body functions like metabolism, mood, sexual function, growth and reproduction.
MEN most commonly affects the following glands:
- Pituitary
- Thyroid
- Parathyroid
- Adrenal
- Pancreas
Who gets multiple endocrine neoplasia?
MEN is usually, but not always, inherited. It can affect people of any age, race or gender. If one parent has MEN, each child has a 50% chance of inheriting it. Genetic counseling is recommended if:
- You or a family member has MEN
- There is a family history of medullary thyroid cancer or endocrine tumors
There are several types of MEN. MEN type 1 (MEN1) and MEN type 2 (MEN2) are the most common.
MEN type 1 (MEN1)
Also known as Wermer syndrome, MEN1 affects about 1 in 30,000 people. It is caused by a mutation in the MEN1 gene, which normally helps control cell growth. When this gene is mutated, it no longer prevents tumors from forming.
People with MEN1 often develop tumors in multiple glands. These tumors are usually benign but may still cause health problems by producing too much hormone or pressing on other tissues. About half of the people with MEN1 will eventually develop cancer.
MEN1 most often causes tumors in:
Parathyroid glands
Nearly all people with MEN1 develop overgrowth of their parathyroid glands, which can lead to overproduction of parathyroid hormone (PTH). This results in high calcium levels in the blood, which can cause kidney stones, bone loss and kidney damage if untreated.
Learn more about parathyroid disease.
Pituitary gland
MEN1 can cause pituitary tumors. Some of these tumors make too much of certain hormones, which can lead to specific health conditions, including infertility, weight gain and breast milk production in people who aren’t pregnant. Other pituitary tumors may not produce hormones but may still cause issues due to pressing on the tissue around them, resulting in low hormone levels. When pituitary tumors are large, they can also affect vision. Most pituitary tumors respond well to medication, though some may require surgery or radiation.
Learn more about pituitary tumors.
Pancreas and duodenum
In MEN1, tumors can develop in the pancreas or in the duodenum, the first part of the small intestine. These tumors may affect hormone production and digestion, and while the duodenum is the most commonly involved section, other parts of the small intestine are rarely affected. Common tumor types include:
- Gastrinomas, which cause Zollinger-Ellison syndrome (ZES), resulting in ulcers and abdominal pain.
- Insulinomas, which can cause low blood sugar. These often require surgery.
Learn more about pancreatic cancer
Other tumors that may occur with MEN1 include:
- Adrenal tumors (usually benign)
- Lipomas (fatty tumors under the skin)
- Carcinoid tumors of the thymus, lungs or stomach
- Skin growths like facial angiofibromas or collagenomas
MEN type 2 (MEN2)
The RET gene makes a protein that helps control how certain cells grow and develop. MEN2 is caused by mutations in the RET gene and has three subtypes:
MEN2A
MEN2A can cause:
- Medullary thyroid cancer (often in young adults)
- Pheochromocytomas (adrenal tumors)
- Paragangliomas (neuron tumors)
- Hyperparathyroidism (elevated parathyroid hormone causing high calcium levels in the blood)
- Cutaneous lichen amyloidosis (an itchy skin condition)
MEN2B
This more aggressive form may cause:
- Medullary thyroid cancer in early childhood
- Pheochromocytomas (adrenal tumors)
- Physical traits such as a tall, slender body
- Benign mouth and tongue tumors
- Digestive issues
- Thickened eyelids and lips
- Curved spine or other bone problems
Doctors may recommend patients with MEN2B have their thyroid removed before cancer develops. The timing of the surgery will depend on the type of RET gene mutation and the patient’s specific evaluation. A genetic counselor can help you and your family decide when and whether to pursue testing and surgery.
Familial medullary thyroid carcinoma (FMTC)
Familial medullary thyroid carcinoma (FMTC) is a type of MEN2, related to MEN2A. It causes medullary thyroid cancer in several family members but does not include the other features of MEN2, such as adrenal gland tumors (pheochromocytomas) or parathyroid problems. FMTC is linked to the same gene as MEN2A but mostly affects the thyroid.
Multiple endocrine neoplasia symptoms
Symptoms of multiple endocrine neoplasia vary depending on the type and which endocrine glands are affected. Some people notice signs early in life, while others may not have symptoms until adulthood. In some cases, tumors are found during routine screening before symptoms appear.
Hormone changes caused by MEN can lead to fatigue, digestive problems, bone pain, unusual growths, mood changes or sexual and fertility issues.
- MEN1: Often affects the parathyroid, pancreas and pituitary glands. Common issues include high calcium levels, digestive problems and hormone imbalances.
- MEN2: Often affects the thyroid and adrenal glands. Features can include growths on the lips or tongue, unusual bone development, a tall, slender body type and medullary thyroid cancer.
Early evaluation and ongoing monitoring are important to detect changes promptly and guide treatment.
Learn more about multiple endocrine neoplasia symptoms
Multiple endocrine neoplasia treatment
Treatment depends on the type of MEN, which glands are affected, and whether tumors are benign or cancerous. Genetic counseling and long-term monitoring are often part of care.
Surgery is commonly used to remove tumors in the parathyroid, pancreas, thyroid or adrenal glands. Medications can help control hormone levels, manage tumors or relieve symptoms. Radiation therapy may be considered for tumors that cannot be fully treated with surgery or medication.
Some tumors may be monitored with active surveillance, with treatment started only if the tumor grows or hormone levels change. Because MEN is lifelong, ongoing follow-up is important to adjust care as needed.
Learn more about multiple endocrine neoplasia treatment
Multiple endocrine neoplasia survival rates
Survival rates for MEN depend on the type of tumors involved and how early they are detected.
- MEN1 tumors are usually benign and manageable with treatment, though some may become cancerous over time.
- MEN2 has a higher risk of medullary thyroid cancer, but early thyroid removal greatly improves outcomes.
Pheochromocytomas, which may occur in MEN2, can cause dangerous blood pressure spikes. While usually not cancerous, they must be treated quickly to avoid serious complications. They are most dangerous during stressful events like surgery or childbirth.
With early diagnosis, expert care and lifelong monitoring, most people with MEN can live long, healthy lives.
Living with multiple endocrine neoplasia
People with MEN require lifelong care to monitor for new tumors and manage hormone levels. This means regular visits with a team of specialists, including endocrinologists, surgeons, genetic counselors, and sometimes oncologists. A typical care plan may include:
- Routine blood tests: These help track hormone levels, calcium, and other markers to detect early changes that may indicate new or growing tumors. Many patients need blood work every few months, though the schedule may vary depending on the tumor type and treatments received.
- Imaging scans: MRI, CT, ultrasound or nuclear medicine scans are often used to visualize tumors. Some scans may happen every year, while others are done more frequently if there are changes in symptoms or lab results.
- Preventive or follow-up surgeries: Surgery may be recommended to remove tumors or prevent complications, such as thyroid removal for MEN2 patients at risk of medullary thyroid carcinoma. Recovery from surgery can affect daily routines, and patients often need short periods of rest and follow-up care.
- Hormone therapy: If tumors affect hormone-producing glands, patients may need medications to replace or block hormones. This can mean daily pills or injections, careful dose monitoring and adjusting therapy as needed based on symptoms or lab results.
- Genetic counseling for family members: Because MEN is inherited, family members may undergo genetic testing and counseling. This often involves discussions about timing of screening, preventive surgery and family planning.
Day-to-day life with MEN involves careful monitoring. The diagnosis and ongoing care can cause fatigue, stress and anxiety, so mental health support or patient groups are valuable.
Maintaining a healthy lifestyle — including a balanced diet, regular exercise, and avoiding smoking or excessive alcohol consumption — supports overall health and can improve treatment outcomes. Despite the need for ongoing vigilance, many people with MEN lead full, active lives while following their care plan.
Learn more about multiple endocrine neoplasia:
- Multiple endocrine neoplasia symptoms
- Multiple endocrine neoplasia diagnosis
- Multiple endocrine neoplasia treatment
We recommend genetic counseling for anyone with MEN or a family history of the disease. Visit our genetic testing page to learn more.
Learn more about clinical trials for Multiple Endocrine Neoplasia (MEN).
10 thyroid myths you shouldn’t believe
Have you ever heard that people with thyroid disorders shouldn’t eat certain vegetables? Or that you can treat an underactive thyroid gland with iodine supplements, and other thyroid disorders with hormone supplements?
If so, you’re not alone. The only problem? None of these claims is accurate. So, before you take any action based upon them, we want to set the record straight on these and seven other common thyroid myths you might’ve heard.
Myth #1: If you’re feeling tired, gaining weight, losing your hair and unable to concentrate, it must be your thyroid.
Fact: These symptoms can be linked to thyroid problems, but they are more often caused by aging, stress, lack of sleep, and poor nutrition. Many people begin experiencing these issues as they get older.
These symptoms may also be caused by chemotherapy or cancer. In any event, they are not always due to thyroid problems.
Myth #2: People with thyroid disorders should avoid certain vegetables.
Fact: Patients with certain types of thyroid cancer may be asked to follow a low-iodine diet temporarily while undergoing diagnostic testing or as a part of their treatment. But people with thyroid disorders can and should eat a healthy, well-balanced diet.
Some people claim that cruciferous vegetables — including broccoli, cauliflower, Brussels sprouts and kale — can interfere with thyroid function. However, these vegetables are still part of a heathy, balanced diet, and you can eat them in moderation, even if you have a thyroid disorder.
Myth #3: You can address thyroid disorders with over-the-counter hormone supplements.
Fact: Many over-the-counter thyroid supplements are not regulated by the Food and Drug Administration (FDA), and there is no oversight on these products, which are made with hormones taken from animals. There is also very little data on their long-term effects. So, we would not recommend them.
Myth #4: You can fix an underactive thyroid with iodine supplements.
Fact: Diet alone cannot cure thyroid problems. But iodine supplements can negatively affect the thyroid gland if taken without a physician’s supervision.
Still, it is very rare for people to be iodine-deficient in the United States. Iodine is usually present in the soil where farmers grow their fruits and vegetables. Also, many foods produced here are fortified with iodine, including:
- dairy products
- eggs
- bread
- salt
- seafood
Myth #5: If you have hypothyroidism, you need a thyroid ultrasound.
Fact: Having hypothyroidism does not automatically mean you need a thyroid ultrasound. You only need an ultrasound if you have signs of a thyroid nodule or other concerns that require further evaluation.
Most people with hypothyroidism do not need routine ultrasounds.
Why come to MD Anderson for multiple endocrine neoplasia treatment?
Multiple endocrine neoplasia (MEN) syndromes are treated in MD Anderson's Endocrine Center, one of the nation's most active programs for diagnosis and treatment of these complex and rare diseases.
We have high level of experience and expertise that is found at few other centers.
Your care is personalized by a team of renowned experts from many specialties. Working closely with each other and with you, they customize your treatment plan and deliver the most advanced therapies with the least impact on your body. This individualized care is important because MEN can affect many processes and parts of the body.
If surgery is needed, our surgeons have vast experience in proven procedures to treat multiple endocrine neoplasia. If multiple endocrine neoplasia runs in your family, we offer the most advanced genetic testing to let you know your risk.
As one of the leaders in endocrine disorders, we are constantly researching new ways to treat MEN-related diseases. This means we are able to offer clinical trials, which may be difficult to find in other programs.
The Endocrine Center at MD Anderson