MEN Syndromes

Multiple endocrine neoplasia (MEN) type I is an inherited disorder in which one or more of your endocrine glands are overactive or form a tumor. The endocrine glands most commonly involved are the pancreas, parathyroid, and pituitary. 

Causes and Risk Factors for 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. 

Signs and Symptoms of MEN I

Symptoms of MEN I vary from person to person and depend on which gland is involved. Symptoms include:

Signs of MEN I may include: 

  • Coma, if low blood sugar is left 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 

Diagnosis of MEN I

Tests used to diagnose tumors involved with MEN I include the following:

Treatments for MEN I

Surgery to remove the diseased gland is the treatment of choice, although a medication called bromocriptine may be used instead for pituitary tumors that release the hormone prolactin. Because your body needs your parathyroid glands to regulate your calcium levels, your doctor usually won’t remove all of your glands initially. Hormone replacement therapy is provided when entire parathyroid glands are removed or do not produce enough hormones. 

In certain cases, medication is the most appropriate treatment. Medications are available to reduce the production of excess stomach acid caused by some tumors and to reduce the risk of ulcers. 


Multiple endocrine neoplasia type 2 (MEN 2) is an extremely rare hereditary disease. Individuals who inherit the gene for MEN 2 will develop over-activity, and certain endocrine glands — most commonly the parathyroid, adrenal, and thyroid glands — will become enlarged. 

Those who inherit the gene for MEN 2 are predisposed to excess hormone production by the parathyroid glands, the central portion of the adrenal gland (the adrenal medulla), or a very specific type of thyroid cancer. Increased hormone production is usually associated with enlargement of these glands. 

You can find out whether you have inherited the MEN 2 gene through genetic testing (predictive genetic testing). This requires only a single blood sample. A negative test result means you do not have MEN 2, nor can you pass MEN 2 to your children. 

If your test result is positive, you should have regular tests for endocrine gland over-activity. This involves periodic blood tests and occasional scans. These blood tests and scans can detect endocrine gland over-activity and adenoma at an early stage. Early detection of endocrine gland over-activity and adenoma enables you to begin treatment before complications develop. 

MEN2 blood tests measure your level of:

  • Parathyroid hormone, calcium, and ionized calcium: used to detect hyperparathyroidism, which is often the first sign of MEN 2
  • Epinephrine: a hormone over-produced by the adrenal gland
  • Calcitonin: the hormone produced by the cells of the thyroid that eventually become malignant (medullary thyroid cancer). Everyone with medullary thyroid cancer will have elevated levels of calcitonin in their blood. 

You can usually control the health problems associated with MEN 2 through regular testing, early diagnosis, and appropriate treatment. Treatment almost always entails surgical removal of the overactive adenomas. Complete removal of the thyroid prior to it becoming cancerous can prevent the development of medullary thyroid cancer. 

Schedule a Thyroid Consult/Appointment  

Patients with diseases of the thyroid and parathyroid come to the Mount Sinai Health System in New York City from all over the world. We provide comprehensive state-of-the-art care based on the latest innovations in the field. Our surgeons are internationally recognized as experts who excel in clinical care and research.

To schedule an appointment, call us at 212-241-9410. You may also request an appointment online or request a telemedicine appointment by emailing