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Multiple endocrine neoplasia (MEN) I



Multiple endocrine neoplasia (MEN) type I is an inherited disorder in which one or more of the endocrine glands are overactive or form a tumor. Endocrine glands most commonly involved include:

  • Pancreas
  • Parathyroid
  • Pituitary
Alternative Names

Wermer syndrome; MEN I


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:

Signs and tests

Signs may include:

  • Coma (if low blood sugar is untreated)
  • High blood calcium level
  • Kidney stones
  • Low blood pressure
  • Low blood sugar
  • Pituitary problems (such as breast discharge from too much prolactin, a hormone that controls breast milk production)

Tests to diagnose tumors involved with MEN I may include:

Support Groups

Expectations (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 treatment.

Calling your health care provider

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


Recurrent tumors may develop.


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.

There is now effective medication to reduce the excess stomach acid production caused by some tumors, and to reduce the risk of ulcers.

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


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


Kronenberg HM. Polyglandular disorders. in: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 250.

National Comprehensive Cancer Network Clinical Practice Guidelines in Oncology: Neuroendocrine Tumors. National Comprehensive Cancer Network; 2009. Version 2.2009.

Review Date: 3/2/2010
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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