Definition of Multiple Endocrine Neoplasia Type I:

Multiple endocrine neoplasia (MEN) I is disorder passed down through families (inherited) in which one or more of the endocrine glands have too much tissue or form a tumor. Endocrine glands include the parathyroid, pancreas, pituitary, adrenals, or thyroid.

Causes, incidence, and risk factors:

MEN I is caused by a defect in a gene called RET. 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 affects men and women equally.

Most persons with MEN I seek medical treatment for a severe form of peptic ulcer disease caused by a tumor in the pancreas and symptoms related to low blood sugar, high blood calcium, kidney stones, or pituitary problems (such as headache).

Risk factors for MEN I include a family history of this disorder, a previous pituitary tumor, and a history of Zollinger-Ellison syndrome.