Multiple endocrine neoplasia, type 1 (MEN 1)


Multiple endocrine neoplasia, type 1 (MEN 1), sometimes called Wermer's syndrome, is a rare disorder that causes tumors in the endocrine glands and parts of the small intestine and stomach. In MEN 1, the endocrine glands — usually the parathyroids, pancreas and pituitary — grow tumors and release excessive amounts of hormones that can lead to disease. However, the tumors are usually noncancerous (benign).

The excess hormones can cause a wide variety of signs and symptoms. These can include tiredness, bone pain, broken bones, kidney stones, and ulcers in the stomach or intestines. MEN 1 can't be cured. But regular testing can detect problems, and doctors can provide treatment as needed.

MEN 1 is an inherited disorder. That means people who have a genetic change that causes MEN 1 can pass it on to their children.


Signs and symptoms of MEN 1 include the following:

  • Tiredness.
  • Bone pain.
  • Broken bones.
  • Kidney stones.
  • Ulcers in the stomach or intestines.

Symptoms are caused by the release of too many hormones in the body.


MEN 1 is caused by a change in the MEN1 gene. That gene controls how the body makes a protein called menin. Menin helps to keep cells in the body from growing and dividing too quickly.

Research has found that there are many different changes in the MEN1 gene that can cause the MEN 1 condition to develop. People who have one of those genetic changes can pass it on to their children. Many people with a change in the MEN1 gene inherit it from a parent. But some people are the first in their family to have a new MEN1 gene change that doesn't come from a parent.

Risk factors

  • Children with a parent who has a genetic change in the MEN1 gene are at risk of inheriting that genetic change and developing MEN 1. A child who has a parent with a genetic change for MEN 1 has a 50% chance of inheriting the same genetic change.
  • Parents and siblings of people who have a change in the MEN1 gene also are at risk of having the same genetic change. That's true even if they have not yet developed symptoms of MEN 1.


To diagnose multiple endocrine neoplasia, type 1 (MEN 1), your doctor will perform a physical exam and review your medical history and family history. You may have a blood test and imaging tests, including the following:

  • Magnetic resonance imaging (MRI).
  • Computerized tomography (CT) scan.
  • Positron emission tomography (PET) scan.
  • Nuclear medicine scans.
  • Endoscopic ultrasound of the pancreas and other scans.

Genetic testing may determine whether someone has a genetic change that causes MEN 1. If so, that person's children are at risk of inheriting the same genetic change and developing MEN 1. Parents and siblings also are at risk of having the genetic change that causes MEN 1.

If no related genetic changes are found in family members, then no further screening tests are needed. However, genetic testing cannot identify all the genetic changes that can cause MEN 1. If genetic testing doesn't confirm MEN 1, but it's likely a person has it, that person, as well as family members, still needs close follow-up with appropriate blood tests and diagnostic imaging.


In MEN 1, tumors can grow on the parathyroids, pancreas and pituitary gland. These tumors can lead to various conditions, all of which can be treated. These conditions and treatments may include:

  • Pituitary tumors. These types of tumors may be treated with surgery or drug therapy.
  • Hyperparathyroidism. Surgery to remove most of the parathyroid glands is the usual treatment for too much parathyroid hormone.
  • Neuroendocrine tumors. These are usually located in the pancreas or small intestine (duodenum). Treatment depends on the type and stage of the tumor.
  • Hypoglycemic syndrome. This condition results when tumors produce too much insulin (insulinomas), causing severely low levels of glucose, which can be life-threatening. Doctors usually recommend surgery and possibly removal of a portion of the pancreas.
  • Zollinger-Ellison syndrome (ZES). ZES can result in tumors that overproduce gastric acid (gastrinomas), leading to ulcers and diarrhea. Doctors may prescribe medication or surgery.
  • Other pancreatic neuroendocrine tumors. These tumors sometimes produce other hormones that can cause various health issues. Treatment of these types of tumors may involve medication, surgery or an ablation procedure. In an ablation procedure your doctor destroys abnormal tissue that may be present.
  • Metastatic neuroendocrine tumors. Disease that has spread to the lymph nodes or liver may be treated with surgery. Surgery options include liver surgery, radiofrequency ablation, cryoablation or chemoembolization.

    Radiofrequency ablation uses high-frequency energy that passes through a needle and causes the surrounding tissue to heat up, killing the nearby cells. Cryoablation involves freezing tumors. And chemoembolization involves injecting strong chemotherapy drugs directly into the liver. When surgery isn't an option, doctors may use other forms of chemotherapy or hormone-based treatments.

  • Adrenal tumors. Most of these tumors can be observed and not treated. However, if the tumors produce hormones or they're large and thought to be cancerous, doctors recommend removing them, usually with minimally invasive surgery.
  • Carcinoid tumors. Carcinoid tumors in people with MEN 1 can develop in the lungs, thymus gland and digestive tract. Surgeons remove these tumors when they haven't spread to other areas. Doctors may use chemotherapy, radiation therapy or hormone-based therapy for advanced cases.

Last Updated Feb 14, 2024

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