MEN type 1

• Multiple endocrine neoplasia (MEN) syndromes are autosomal dominantly inherited conditions characterised by tumours of endocrine glands.
• is caused by a mutation to the MEN 1 tumour suppressor gene and is characterised by the three P’s:

  • Primary hyperparathyroidism
  • Pituitary adenoma
  • Pancreatic tumours
• Primary hyperparathyroidism:

  • Occurs in over 90%
  • Presents earlier than sporadic cases
  • High rate of recurrence following excision
• Pituitary adenomas:

  • Affect around 50% of patients
  • Can affect a number of cell types
  • Hyperprolactinaemia
  • Acromegaly
  • Excess ACTH - cushing's disease
• Pancreatic tumours:

  • Insulinomas - tumours of the beta cells. Can cause severe hypoglycaemia
  • Gastrinomas - tumours of gastrin secreting G cells. Zollinger-Ellison syndrome. Leads to peptic ulcers.
• MEN 1 is defined as the presence of two or more MEN 1 tumour types.
• Hormonal tests:

  • Serum calcium
  • PTH
  • Prolactin
  • Gastrin levels
  • Pituitary function
• Unlike MEN 2 there is no clear evidence of the benefit of using DNA testing in the general screening process of MEN 1.
• Management:

  • hyperparathyroidism - surgery, bisphosphonates
  • Pituitary adenoma - Surgery, correction of hormones
  • Pancreatic tumours - Diazoxide for insulinomas or subtotal pancreatectomy. PPIs for gastrinomas.