Multiple Endocrine Neoplasia (MEN) is a group of genetic conditions (autosomal dominant) characterised by the formation of hormone-producing tumours in multiple endocrine organs.

• pituitary
• thyroid
• parathyroid
• adrenal
• pancreas

Multiple Endocrine Neoplasia-1 (MEN-1) features

• Caused by mutation in the MEN 1 gene

• Parathyroid: hyperplasia/adenomas = hypercalcaermia, kidney stones

• Pancreas:

  • gastrinoma: +HCl = peptic ulcers, abdo pain, vomitting),
  • insulinoma: hypoglycaemia

• Pituitary adenomas

  • prolactinoma - galactorrhea in women and gynae in men
  • Excess GH

Multiple Endocrine Neoplasia-2a (MEN-2a) features

• Caused by mutation in the RET gene

• Thyroid: medullary thyroid cancer

• Adrenal: pheochromocytoma

• Parathyroid: hyperplasia/adenomas (in MEN2a only about half of patients develop this)