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, such as tiredness, bone pain, fractures and kidney stones, as well as stomach or intestinal ulcers. Although MEN 1 can't be cured, regular testing can detect problems, and doctors can provide treatment as needed.

MEN 1 is an inherited disorder, meaning people who have the gene mutation can pass it on to their children. Each child has a 50 percent chance of inheriting the disorder.

  • Experience and expertise. Although MEN 1 is rare, you can rely on the expertise and experience of Mayo Clinic specialists to diagnose and provide the best treatment for this complicated disorder. Specialists at Mayo provide the latest interventions for both primary tumors and those that have spread (metastasized). Mayo Clinic specialists treat about 125 people with MEN 1 each year.
  • Team approach. Mayo Clinic specialists work as a team to listen, counsel and treat people who have MEN 1. Depending on your specific needs and related conditions, the team may include experts in endocrinology, endocrine surgery, gastroenterology, neurosurgery, oncology, interventional radiology, radiation oncology, chest (thoracic) surgery, liver (hepatobiliary) surgery, medical genetics and other areas if needed.

At Mayo Clinic, we assemble a team of specialists who take the time to listen and thoroughly understand your health issues and concerns. We tailor the care you receive to your personal health care needs. You can trust our specialists to collaborate and offer you the best possible outcomes, safety and service.

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The diagnosis of MEN 1 includes gathering a thorough medical and family history, as well as a physical exam to look for signs and symptoms of excess hormones. Then, blood is drawn to check hormone levels, and imaging tests may be done to look for endocrine system tumors.

If someone has already been diagnosed with MEN 1, imaging tests may be done even if hormone levels aren't yet abnormal.

Imaging tests may include magnetic resonance imaging (MRI), computerized tomography (CT), positron emission tomography (PET), nuclear medicine scans (for example, octreotide scintigraphy), endoscopic ultrasound of the pancreas and other scans. In tests that involve radiation, specialists carefully monitor doses to avoid the risk of radiation overexposure.

Conditions and testing related to MEN 1 may include:

  • Pituitary tumors. At Mayo Clinic, monitoring for pituitary tumors in people with MEN 1 includes an MRI of the pituitary gland and measuring certain hormones in your blood. If MRI results are abnormal, your doctor may do other pituitary testing. The most common pituitary gland problem in MEN 1 is a small tumor that releases too much prolactin (prolactinoma), which can often be treated without surgery.
  • Hyperparathyroidism. Specialists diagnose overactive parathyroid glands (hyperparathyroidism) in people with MEN 1 based on parathyroid hormone (PTH) and calcium levels. Almost all people with MEN 1 develop hyperparathyroidism. At Mayo Clinic, specialists use the latest technology for diagnosis, such as parathyroid sestamibi subtraction scanning with SPECT CT imaging; ultrasound, which may include fine-needle aspiration with parathyroid hormone measurement; and 4-D CT scanning.
  • Pancreatic and duodenal neuroendocrine tumors. Specialists may use blood tests to detect substances produced by tumors (tumor markers) in the blood of people with MEN 1. Sometimes these changes can be found before symptoms appear. Imaging is often done with CT or MRI using specialized procedures to detect small tumors in the pancreas. Mayo specialists may also use endoscopic ultrasound to detect endocrine tumors in the first part of the small intestine (duodenum) and the pancreas. Nuclear medicine scans, such as octreotide scintigraphy, may be used to confirm the presence and locations of pancreatic neuroendocrine tumors.
  • Other tumors and findings. Tumors may arise in the lungs, thymus gland (carcinoid tumors) and esophagus (leiomyoma). Doctors will usually perform periodic imaging tests of these areas. People with MEN 1 often have skin tumors; these are benign and should be removed only if they cause symptoms.

Genetic consultation and testing

Mayo Clinic experts encourage people who have a MEN 1 genetic mutation to have periodic tests to look for tumors and other related medical problems. Experts recommend that family members at risk of MEN 1 get genetic testing or start getting clinical screening in childhood or the early teen years because problems, such as hyperparathyroidism, can develop before the age of 20. Screening can begin as early as 5 years old.

You and your family can meet with genetic specialists to review the pros and cons of genetic testing. At this meeting, you can learn:

  • How and where the test is performed
  • The probability of a positive test
  • How a positive test would influence current medical management
  • How a positive test would provide options for at-risk family members
  • Which family members might be at risk and need further evaluation

Genetic testing may determine whether someone has a genetic mutation causing MEN 1. If someone has a mutation, his or her children are at risk of inheriting the mutation and developing MEN 1. Parents and siblings also are at risk of having the mutation even if they have not yet developed symptoms. If no related genetic changes are found in family members, then no further screening tests are needed. However, genetic testing doesn't uncover all MEN 1 genetic mutations. If genetic testing doesn't confirm MEN 1, but it's likely a person has it, he or she and his or her family members still need close follow-up with appropriate blood tests and diagnostic imaging.

Mayo Clinic experts have a wealth of expertise in the latest interventions for the tumors associated with multiple endocrine neoplasia, type 1 (MEN 1) if they are in one area (localized) or if they have spread (metastasized). Treatment for MEN 1 depends on each person's situation and related conditions. In the early stages, specialists may recommend surgery to remove tumors as well as drug therapy to regulate hormones. If a tumor is cancerous and has spread, doctors may use surgery, radiation, chemotherapy and treatments such as radiofrequency ablation or chemoembolization.

Below are examples of related conditions and treatment options:

  • Pituitary tumors. Doctors may recommend surgery or drug therapy based on the type of pituitary tumor. They will recommend regular follow-up screening.
  • Hyperparathyroidism. Most people with MEN 1 will develop too much calcium in the blood (hypercalcemia) due to too much parathyroid hormone (hyperparathyroidism) by the time they reach age 50. This can lead to the development of kidney stones, osteoporosis and other symptoms. Regular screening for people at risk can detect hyperparathyroidism before complications occur.

    The most common treatment is surgery to remove three and a half of the four parathyroid glands (subtotal parathyroidectomy). The half gland that's left can maintain normal levels of calcium. However, with time, the remaining parathyroid tissue usually starts to overproduce parathyroid hormone again.

    When re-treatment is required, options include a second surgery, transplantation of parathyroid tissue to the arm or chest wall, or alcohol injection into a portion of the parathyroid gland under ultrasound guidance.

  • Neuroendocrine tumors. People with MEN 1 frequently develop neuroendocrine tumors, also called islet cell tumors. These are usually located in the pancreas or small intestine (duodenum). These can become cancerous (malignant), so early detection and intervention is important. Some neuroendocrine tumors overproduce a normal pancreatic hormone, which results in symptoms related to high levels of the specific hormone. Treatment depends on the type and stage of the tumor.
  • Hypoglycemic syndrome. Some people with MEN 1 develop tumors that produce too much insulin (insulinomas). Although the tumors are most often not cancerous, they can cause severely low levels of glucose, which can be life-threatening. More than one tumor may be present and doctors usually recommend surgery. In removing the tumor or tumors, often a portion of the normal pancreas needs to be removed (distal pancreatectomy).
  • Zollinger-Ellison syndrome (ZES). Many people with MEN 1 develop ZES, which involves tumors that result in overproduction of gastric acid (gastrinomas) leading to ulcers and diarrhea. Doctors may prescribe medication such as proton pump inhibitors (PPIs). However, extensive surgery may be necessary to slow the progress of the disease.
  • Metastatic neuroendocrine tumors. If your disease is more advanced — for example, if it has spread to the lymph nodes or liver — treatment may involve liver surgery, radiofrequency ablation or injection of strong chemotherapy drugs directly into the liver (chemoembolization). When surgery is not an option, doctors may use other forms of chemotherapy or hormone-based treatments.
  • Adrenal tumors. Some people with MEN 1 develop tumors in their adrenal glands. Most tumors do not produce hormones and are not cancerous, so they 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 laparoscopic surgery.
  • Carcinoid tumors. Carcinoid tumors in people with MEN 1 can develop in the lungs, thymus gland and gastrointestinal (GI) 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.

Mayo Clinic works with hundreds of insurance companies and is an in-network provider for millions of people. In most cases, Mayo Clinic doesn't require a physician referral. Some insurers require referrals or may have additional requirements for certain medical care. All appointments are prioritized on the basis of medical need.

Specialists at Mayo Clinic's campus in Arizona treat adults with MEN 1. Medical specialists involved in testing, diagnosis and treatment vary, depending on the symptoms and disease progression. The team may include specialists in endocrinology, general surgery, gastroenterology, neurosurgery, radiation oncology and other areas if needed.

For appointments or more information, call the Central Appointment Office at 800-446-2279 (toll-free) 8 a.m. to 5 p.m. Mountain Standard Time, Monday through Friday or complete an online appointment request form.

Specialists at Mayo Clinic's campus in Florida treat adults with MEN 1. Medical specialists involved in testing, diagnosis and treatment vary, depending on the symptoms and disease progression. The team may include specialists in endocrinology, general surgery, gastroenterology, neurosurgery, radiation oncology, nuclear medicine, medical genetics and other areas if needed.

For appointments or more information, call the Central Appointment Office at 904-953-0853 8 a.m. to 5 p.m. Eastern time, Monday through Friday or complete an online appointment request form.

Specialists at Mayo Clinic's campus in Minnesota treat adults and children with MEN 1. Medical specialists involved in testing, diagnosis and treatment vary, depending on the symptoms and disease progression. The team may include specialists in endocrinology, pediatric endocrinology, general surgery, gastroenterology, neurosurgery, radiation oncology and other areas if needed.

For appointments or more information, call the Central Appointment Office at 507-538-3270 7 a.m. to 6 p.m. Central time, Monday through Friday or complete an online appointment request form.

Symptoms of MEN 1 generally don't occur until people are in their 20s or 30s. However, at-risk children may be tested for the genetic mutation associated with MEN 1.

If test results confirm a genetic mutation, specialists at Mayo Clinic may recommend regular screening for hyperparathyroidism and other signs of the disorder. Children are most likely to have pituitary tumors or abnormalities in parathyroid hormone levels. Their treatment is similar to that of adults.

For appointments or more information, call the Central Appointment Office at 507-538-3270 7 a.m. to 6 p.m. Central time, Monday through Friday or complete an online appointment request form.

See information on patient services at the three Mayo Clinic locations, including transportation options and lodging.

See a list of publications by Mayo doctors on multiple endocrine neoplasia, type 1 (MEN 1) on PubMed, a service of the National Library of Medicine.

Sep. 17, 2014