Sunday, 26 September 2010

MRCP revision battle 21.2: Glucagon and glucagonoma

Lets quickly recap glucagon from our med school days before we move on to the more exotic beast of glucagonoma...

Glucagon is a peptide hormone secreaed from the alpha cells of the islets of langerhans.

It results in raised blood glucose by:
  • increasing gluconeogenesis in the liver
  • increasing lipolysis

Glucagon is secreted in response to low blood glucose, raised catecholamines and raised plasma amino acids.
Glucagon secretion is inhibited by insulin, ketones in the blood, somatostatin and free fatty acids in the blood

A glucagonoma is a very rare tumour of the alpha cells of the islets of langerhans which secretes glucagon.

It results in:
  • massively raised levels of glucagon
  • diabetes mellitus
  • hypoaminoacidaemia (as GNG is using up protein)
  • anaemia
  • necrolytic migratory erythema

Necrolytic migratory erythema is a red, blistering rash which is the presenting feature of a glucagonoma in 70% of cases.

Glucagonomas can be associated with MEN 1.

Treatment of a glucagonoma is ocreotide and surgery; prognosis is poor

For the really keen:

For the rest of us, its onwards to battle 21.3!