Multiple Endocrine Neoplasia Type 1

Individuals who have multiple endocrine neoplasia type 1 (MEN1) are more likely to develop multiple tumors of their endocrine glands. Any person who has two of the three main endocrine tumors (parathyroid, pituitary, and pancreatic) has MEN1.

Tumors associated with MEN1 are generally non-cancerous, but health problems are caused by the excess hormones they can create. There is nearly a 100 percent risk to develop parathyroid tumors in people who have MEN1.


Symptoms of parathyroid tumors include weak bones, kidney stones, and feelings of fatigue. People with MEN1 are also at high risk to develop pituitary tumors, pancreatic tumors, bronchial and/or thymic carcinoids, and adrenocortical tumors. Insulinomas, which are formed in the pancreas, are usually benign, but cause hypoglycemia. Gastrinomas, another type of pancreatic tumor, may become cancerous.

Pituitary tumors can cause menstrual irregularity in women and reduced libido in men. Other symptoms such as headache and decreased vision may occur. Patients with MEN1 are also more likely to have non-endocrine benign tumors such as facial angiofibromas, collagenomas, and lipomas.


Many steps can be taken to reduce the risk of tumors and cancer associated with MEN1. Anyone with MEN1 should have yearly biochemical testing, as well as head and abdominal imaging every three to five years. Removal of the thyroid should be considered as well.

Our genetic counselors can work with you to determine your risk to have MEN1. Your genetic counselor can speak with you about genetic testing as an option. Genetic testing is particularly helpful in determining whether family members have MEN1.

MEN1 and MEN2 are two separate conditions that should not be confused with each other.