Pituitary adenoma

MEN-1

Multiple endocrine neoplasia type 1 (MEN-1) is an autosomal dominant condition associated with pituitary adenomas in 40% to 60% of patients, caused by mutations in the MEN-1 gene on chromosome 11q13. MEN-1 may be associated with nonfunctional or functional pituitary tumors, among which prolactinoma is the most common. Screening may be offered to patients with MEN-1 or with features resembling them (parathyroid hyperplasia ± pituitary adenomas ± pancreatic endocrine tumors). When a mutation is found, further testing in other relatives can become much easier.[52]Brandi ML, Gagel RF, Angeli A, et al. Guidelines for diagnosis and therapy of MEN type 1 and type 2. J Clin Endocrinol Metab. 2001 Dec;86(12):5658-71. http://www.ncbi.nlm.nih.gov/pubmed/11739416?tool=bestpractice.com Asymptomatic offspring, brothers, or sisters of a person with MEN-1 are born with a 50% chance of having inherited the gene and can be offered genetic testing. By age 40 most individuals carrying the MEN-1 gene are hypercalcemic; indeed, the absence of hypercalcemia by around age 60 is strongly against the diagnosis of MEN-1 and in most cases no further testing is necessary. Neoplasia of pancreatic islet cells is the second most common manifestation of MEN-1 and eventually occurs in 80% of patients.

Patients known to have the genetic mutation need to be screened with serum calcium, neuroendocrine tumor markers including gastrin, serum prolactin and IGF-1, and periodic pituitary and abdominal imaging. Hyperparathyroidism, most often the first sign of MEN-1, can usually be detected by annual blood test between the ages of 5 and 50. For this reason screening has been recommended as early as age 5 for children at risk for MEN-1.