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Multiple endocrine neoplasia (MEN) I

Multiple endocrine neoplasia (MEN) type I is a disease passed down through families, in which one or more of the endocrine glands are overactive or form a tumor. Endocrine glands most commonly involved include:

  • Pancreas
  • Parathyroid
  • Pituitary


MEN I is caused by a defect in a gene that carries the code for a protein called menin. The condition causes tumors of various glands to appear in the same person, but not necessarily at the same time.

The disorder may occur at any age, and it affects men and women equally. A family history of this disorder raises your risk.


Symptoms vary from person to person, and depend on which gland is involved. They may include:

Exams and Tests

The health care provider will perform a physical exam and ask questions about your medical history and symptoms. The following tests may be done:


Surgery to remove the diseased gland is the treatment of choice. A medication called bromocriptine may be used instead of surgery for pituitary tumors that release the hormone prolactin.

The parathyroid glands, which control calcium production, can be removed. However, because it is difficult for the body to regulate calcium levels without these glands, a total parathyroid removal is usually not done initially.

Medicine is available to decrease the excess stomach acid production caused by some tumors (gastrinomas), and to reduce the risk of ulcers.

Hormone replacement therapy is given when entire glands are removed or do not produce enough hormones.

Outlook (Prognosis)

Pituitary and parathyroid tumors are usually noncancerous (benign), but some pancreatic tumors may become cancerous (malignant) and spread to the liver. These can lower life expectancy.

The symptoms of peptic ulcer disease, low blood sugar, excess calcium in the blood, and pituitary dysfunction usually respond well to appropriate treatment.

Possible Complications

The tumors can keep coming back. Symptoms and complications depend on which glands are involved. Regular check-ups by your health care provider are essential.

When to Contact a Medical Professional

Call your health care provider if you notice symptoms of MEN I or have a family history of this condition.


Screening close relatives of people affected with this disorder is recommended.

Alternative Names

Wermer syndrome; MEN I


Kronenberg HM. Polyglandular disorders. In: Goldman L, Ausiello D, eds.Goldman's Cecil Medicine

. National Comprehensive Cancer Network; 2011. Version 1.2011.National Comprehensive Cancer Network Clinical Practice Guidelines in Oncology: Neuroendocrine Tumors

Update Date 3/23/2014

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