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Multiple Endocrine Neoplasia Type 1
Multiple Endocrine Neoplasia Type 1 (MEN1) is an inherited disorder that affects the endocrine glands. It is sometimes called multiple endocrine adenomatosis or Wermer's syndrome, after one of the first doctors to recognize it. MEN1 is quite rare, occurring in about 3 to 20 persons out of 100,000. It affects both sexes equally and shows no geographical, racial, or ethnic preferences.
Endocrine glands are different from other organs in the body because they release hormones into the bloodstream. Hormones are powerful chemicals that travel through the blood, controlling and instructing the functions of various organs. Normally, the hormones released by endocrine glands are carefully balanced to meet the body's needs.
In patients with multiple endocrine neoplasia type 1, sometimes multiple endocrine glands, such as the parathyroid, the pancreas, and the pituitary become overactive at the same time. Most people who develop overactivity of only one endocrine gland do not have MEN1.
How does Multiple Endocrine Neoplasia Type 1 affect the endocrine glands?
The Parathyroid Glands
The parathyroids are the endocrine glands earliest and most often affected by MEN1. The human body normally has four parathyroid glands, which are located close to the thyroid gland in the front of the neck. The parathyroids release into the bloodstream a chemical called parathyroid hormone, which helps maintain a normal supply of calcium in the blood, bones, and urine.
In multiple endocrine neoplasia type 1, all four parathyroid glands tend to be overactive. They release too much parathyroid hormone, leading to excess calcium in the blood. High blood calcium, known as hypercalcemia, can exist for many years before it is found by accident or by family screening. Unrecognized hypercalcemia can cause excess calcium to spill into the urine, leading to kidney stones or kidney damage.
Nearly everyone who inherits a susceptibility to MEN1 (a "cancer") will develop overactive parathyroid glands (hyperparathyroidism) by age 50, but the disorder can often be detected before age 20. Hyperparathyroidism may cause no problems for many years or it may cause problems such as tiredness, weakness, muscle or bone pain, constipation, indigestion, kidney stones, or thinning of bones.
Treatment of Hyperparathyroidism.
It is sometimes difficult to decide whether hyperparathyroidism in multiple endocrine neoplasia type 1 is severe enough to need treatment, especially in a person who has no symptoms. The usual treatment is an operation to remove the three largest parathyroid glands and all but a small part of the fourth. After parathyroid surgery, regular testing of blood calcium should continue, since the small piece of remaining parathyroid tissue can grow larger and cause recurrent hyperparathyroidism. People whose parathyroid glands have been completely removed by surgery must take daily supplements of calcium and vitamin D to prevent hypocalcemia (low blood calcium).
Treatment of Gastrinomas.
About one in three patients with multiple endocrine neoplasia type 1 has gastrin-releasing tumors, called gastrinomas. (The illness associated with these tumors is sometimes called Zollinger-Ellison syndrome.) The ulcers caused by gastrinomas are much more dangerous than typical stomach or intestinal ulcers; left untreated, they can cause rupture of the stomach or intestine and even death.
The gastrinomas associated with multiple endocrine neoplasia type 1 are difficult to cure by surgery, because it is difficult to find the multiple small gastrinomas in the pancreas and small intestine. In the past, the standard treatment for gastrinomas was the surgical removal of the entire stomach to prevent acid production. The mainstay of treatment is now very powerful medicines that block stomach acid release, called acid pump inhibitors. Taken by mouth, these have proven effective in controlling the complications from high gastrin in most cases of Zollinger-Ellison syndrome.
Treatment of Prolactinomas.
The pituitary gland becomes overactive in about one of four persons with multiple endocrine neoplasia type 1. This overactivity can usually be traced to a very small, benign tumor in the gland that releases too much prolactin, called a prolactinoma. High prolactin can cause excessive production of breast milk or it can interfere with fertility in women or with sex drive and fertility in men.
Some prolactinomas are small, and treatment may not be needed. If treatment is needed, a very effective type of medicine known as a dopamine agonist can lower the production of prolactin and shrink the prolactinoma. Occasionally, prolactinomas do not respond well to this medication. In such cases, surgery, radiation, or both may be needed.
Are the tumors associated with multiple endocrine neoplasia type 1 cancerous?
The overactive endocrine glands associated with MEN1 may contain benign tumors, but usually they do not have any signs of cancer. Benign tumors can disrupt normal function by releasing hormones or by crowding nearby tissue. For example, a prolactinoma may become quite large in someone with MEN1. As it grows, the tumor can press against and damage the normal part of the pituitary gland or the nerves that carry vision from the eyes. Sometimes impaired vision is the first sign of a pituitary tumor in multiple endocrine neoplasia type 1.
Another type of benign tumor often seen in people with MEN1 is a plum-sized, fatty tumor called a lipoma, which grows under the skin. Lipomas cause no health problems and can be removed by simple cosmetic surgery if desired. These tumors are also fairly common in the general population.
Benign tumors do not spread to or invade other parts of the body. Cancer cells, by contrast, break away from the primary tumor and spread, or metastasize, to other parts of the body through the bloodstream or lymphatic system.
The pancreatic islet cell tumors associated with multiple endocrine neoplasia type 1 tend to be numerous and small, but most are benign and do not release active hormones into the blood.
Eventually, about half of MEN1 cases will develop a cancerous pancreatic tumor or a cancerous carcinoid tumor.
Treatment of Pancreatic Endocrine Cancer in multiple endocrine neoplasia type 1.
Since the type of pancreatic endocrine cancer associated with MEN1 can be difficult to recognize, difficult to treat, and very slow to progress, doctors have different views about the value of surgery in managing these tumors.
One approach is to "watch and wait," using medical, or nonsurgical treatments. According to this school of thought, pancreatic surgery has serious complications, so it should not be attempted unless it will cure a tumor that is secreting too much hormone.
Another school advocates early surgery, perhaps when a tumor grows to a certain size, to prevent or remove pancreatic endocrine cancer in multiple endocrine neoplasia type 1 (even if it does not over secrete a hormone) before it spreads and becomes dangerous. There is no clear evidence, however, that aggressive surgery to prevent pancreatic endocrine cancer from spreading actually leads to longer survival for patients with MEN1. This is partly because these complex operations can have their own side effects.
Doctors agree that excessive release of certain hormones (such as gastrin) from pancreatic endocrine cancer in MEN1 needs to be treated, and medications are often effective in blocking the effects of these hormones. Some tumors, such as insulin-producing tumors of the pancreas, are usually benign and single and are curable by pancreatic surgery. Such surgery needs to be considered carefully in each patient's case.
Can multiple endocrine neoplasia type 1 be cured?
There is no cure for multiple endocrine neoplasia type 1 itself, but most of the health problems caused by MEN1 can be recognized at an early stage and controlled or treated before they become serious problems.
If you have been diagnosed with MENl, it is important to get periodic checkups because MEN1 can affect different glands, and even after treatment, residual tissue can grow back. Careful monitoring enables your doctor to adjust your treatment as needed and to check for any new disturbances caused by multiple endocrine neoplasia type 1. Most MEN1 cases will have a long and productive life.
Information obtained from National Institute of Health