Multiple endocrine neoplasia or MEN 1 is an inherited disorder that causes tumors in the endocrine glands and the duodenum, the first part of the small intestine. MEN1 is sometimes called multiple endocrine adenomatosis or Wermer's syndrome, after one of the first doctors to recognize it. MEN1 is rare, occurring in about one in 30,000 people. The disorder affects both sexes equally and shows no geographical, racial, or ethnic preferences.
Screening may be offered to persons with MEN1 or with features resembling them. Affected relatives of persons with MEN1 can be tested. Asymptomatic offspring, brothers, or sisters of a person with MEN1 were born with a 50 percent chance of having inherited the gene; they too can be offered gene testing. While gene testing for any genetic disease can be definitive at any age, it is usually not offered to children below age 18 unless the test outcome would have an important effect on their medical treatment.
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).