What Is Multiple Endocrine Neoplasia: Type 1 (MEN-1)?

Multiple endocrine neoplasia is a group of disorders that leads to tumors (growth of tissue) in different endocrine glands (the system that both makes and regulates hormones). There are several types of multiple endocrine neoplasia. One common type of this disorder is multiple endocrine neoplasia type 1 (or MEN-1). It is also known as Wermer syndrome.

MEN-1 is a genetic condition caused by mutations (changes) in the MEN1 gene. This gene usually prevents the growth of tumors. In people with MEN-1, the mutation prevents the gene from working properly. This can lead to the growth of multiple tumors in the endocrine system and elsewhere.

What Are the Signs and Symptoms of MEN-1?

There are many symptoms related to MEN-1. Most occur because of increased secretion (production) of certain hormones.

Common conditions associated with MEN-1 include:

  • Endocrine tumors in the pancreas, pituitary gland and parathyroid glands
  • Hyperparathyroidism, a condition in which the parathyroid glands (four small glands that lie behind the thyroid gland, a butterfly-shaped gland in the front of the neck) become overactive and disrupt the balance of calcium and phosphorus in blood, causing high levels of calcium and low levels of phosphorus. This may in turn be associated with:
    • Kidney stones
    • Fragile bones
  • Pituitary tumors, which commonly include tumors that make too much prolactin (prolactinomas), or ACTH (a hormone that stimulates that adrenal glands to make cortisol), or sometimes growth hormone. Symptoms are related to increased secretion of the specific hormone
  • Tumors in the stomach, duodenum or pancreas
    • Zollinger-Ellison syndrome, a condition where the tumor (known as a gastrinoma) causes the stomach to make too much acid. This in turn causes ulcers (sores) in the stomach or upper intestine
    • Pancreatic tumors which include tumors that make too much insulin (insulinomas), as well as other hormone secreting tumors
  • Non-endocrine tumors
    • Collagenomas
    • Lipomas, leiomyomas, meningiomas, and ependymomas
    • Facial angiofibromas, which are small red bumps that grow on the face, especially around the nose and cheeks

Did You Know...?

Not all tumors are dangerous. Tumors can be benign (non-cancerous) or malignant (cancerous). The tumors caused by MEN-1 usually lead to an increased secretion of certain hormones. They may or may not be malignant.

Rev. 11/2019. Mass General for Children and Massachusetts General Hospital do not endorse any of the brands listed on this handout. This handout is intended to provide health information so that you can be better informed. It is not a substitute for medical advice and should not be used to treatment of any medical conditions.