MEN Syndromes | Endocrinology and Diabetes

Endocrinology and Diabetes

Multiple Endocrine Neoplasia (MEN) Syndromes

MEN syndromes are inherited disorders that cause tumors to form in hormone-producing glands. Our endocrine disorder specialists offer advanced care for all types of MEN syndromes.

Medically reviewed by Claire Graves, M.D. on Dec. 04, 2023.

Female health care provider talking to female patient in exam room.

What Are Multiple Endocrine Neoplasia (MEN) Syndromes?

MEN syndromes are rare, inherited conditions that cause tumors to form in glands in your endocrine system. This type of endocrine tumor syndrome causes your glands to make excess hormones. Noncancerous (benign) or cancerous (malignant) tumors may also form in organs and tissues.

The most common treatment for MEN syndromes is surgery. UC Davis Health endocrine surgeons treat MEN syndromes by removing endocrine tumors and affected glands.  


Types of Multiple Endocrine Neoplasia (MEN) Syndromes

There are different types of MEN syndromes: 

  • Type 1 (MEN1): Tumors that are usually noncancerous form in your parathyroid glands. Tumors may also affect your pancreas, pituitary glands and adrenal glands. Wermer syndrome is another name for MEN1.
  • Type 2A (MEN2A): This type poses a high risk of thyroid cancer. Potentially cancerous tumors may also form in adrenal or parathyroid glands.
  • Type 2B (MEN2B): You may develop thyroid cancer and adrenal gland tumors. You also have noncancerous tumors on your lips, tongue and eyelids. (This type used to be known as type 3.)
  • Type 4 (MEN4): Tumors may form in one or more parathyroid gland. Tumors may also form in the pancreas, gastrointestinal (GI) tract, and pituitary glands.

MEN Syndromes Symptoms

MEN syndrome symptoms depend on the type and affected glands. Some mild symptoms can be easy to dismiss.

Common Symptoms

Signs you have a MEN syndrome include:

  • Digestive problems, including constipation, diarrhea, stomach pain, reflux and nausea
  • Fatigue and muscle weakness
  • Increased thirst and urination
  • Joint and bone pain
  • Kidney (renal) stones
  • Muscle weakness
  • Swollen hands and feet

Emergency Symptoms

Certain MEN syndromes can cause dangerously high blood pressure or extremely low blood sugar. Seek immediate care if you experience:

  • Confusion
  • Heart palpitations
  • Profuse sweating
  • Shakiness
  • Vision changes

Causes of MEN Syndromes

Various gene changes (mutations) cause MEN syndromes. The affected gene determines the syndrome type.

Family History

A parent with a MEN syndrome has a 50% chance of passing the relevant gene mutation to each of their children. Only one parent needs to have the genetic mutation for a child to be at risk.

De Novo Mutation

Less commonly, a person with no family history of MEN syndromes develops the condition. The genetic mutation occurs for no apparent reason. This is called a de novo mutation.


Diagnosis and Testing for MEN Syndromes

We offer complete and in-depth testing for familial (genetic) endocrine disorders, including MEN syndromes. These tests help our experts determine the MEN syndrome type and disease severity.

You may get:

  • Blood and urine tests to measure hormone levels
  • Genetic tests to check for gene mutations
  • Medical imaging tests to look for tumors

Treatments for MEN Syndromes

Treatments for MEN syndromes depend on the type, as well as the affected glands or organs. Possible treatments may include:

Endocrine Surgery

Endocrine surgery removes endocrine tumors and other affected glands or organs. Many people with MEN syndromes also have surgery to remove the thyroid gland (thyroidectomy).


If surgeons remove certain glands like your thyroid, you’ll need to take daily hormone medications to replace the missing hormones. Some medications can also lower high hormone levels caused by tumors and overactive glands.

Cancer Treatments

Chemotherapy or radiation therapy can shrink tumors caused by endocrine system cancers. These treatments can also help if cancer spreads.


Preventing MEN Syndromes

You can’t prevent the gene change that causes MEN syndromes. However, certain steps may lower your risk of cancer or passing on the gene mutation.

Genetic Testing

If you have a gene mutation that causes MEN syndromes and want to have children, you may consider in vitro fertilization (IVF) and preimplantation genetic diagnosis (PGD). PGD tests embryos for certain genetic diseases. A provider implants embryos that don’t have the mutated gene. Our reproductive endocrinology experts can help. 

Preventive Surgery

People with MEN2A or MEN2B are at high risk for an aggressive type of thyroid cancer. Your provider may recommend surgery to remove your thyroid gland before cancer has a chance to develop or spread.

Who does it affect?

1 in 30KPeople have MEN1

Familial risk

50%Chance of passing the gene mutation that causes MEN syndromes to a child

Sources: MedlinePlus: Multiple Endocrine Neoplasia

American Society of Clinical Oncology: Multiple Endocrine Neoplasia Type 1

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