Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant familial tumor syndrome (also termed Wermer syndrome) in which persons develop tumors of the parathyroid glands, the enteropancreatic neuroendocrine system, the anterior pituitary gland, and the skin. The most common endocrine tumors are parathyroid tumors that cause hyperparathyroidism and hypercalcemia. Other tumors include gastrinomas, insulinomas, prolactinomas, and carcinoid tumors.
The frequency of multiple endocrine neoplasia type 1 (MEN1) is estimated to be 1 case in 30,000 persons. Benign endocrine and cutaneous tumors cause morbidity, and malignancies cause most mortality (see Complications) in multiple endocrine neoplasia type 1 (MEN1). Screening may be offered to persons with MEN1 or with features resembling them. Affected relatives of persons with MEN1 can be tested.
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).