Iron Homeostasis

Describe the normal nutritional requirements

Approximately 3-5g of iron is found in the body as:

  • Oxygen-carrying globin molecules
    Haemoglobin (~70%) and myoglobin (~5%).
  • Catalyst for biological reactions (~25%)
    Catalase, peroxidase, and cytochromes all require iron.


Dietary iron comes in two forms:

  • Haeme groups
    Directly absorbed via specialised transport proteins.
  • Dietary iron salts
    • Ferrous (Fe2+) iron is soluble, and is absorbed via facilitated diffusion across the enterocyte membrane
      • Reduced acidity of the stomach will reduce the absorption of ferrous iron
    • Ferric (Fe3+) iron precipitates when pH > 3, and so cannot be absorbed independently by the small bowel.
      • A pathway may exist for absorption of ferric iron from soluble chelates
  • Once in the enterocyte, iron can be:
    • Stored, bound to ferritin
    • Transported via ferroportin out of the enterocyte, where it is then oxidised to ferrous iron and bound to transferrin


  • Excretion is uncontrolled
  • Regulation of iron levels is only by absorption
  • Hepcidin is a liver protein which inhibits the action of ferroportin
    • High hepcidin prevents iron transport from the enterocyte
    • Hepcidin is deficient in haemochromatosis


  1. Chambers D, Huang C, Matthews G. Basic Physiology for Anaesthetists. Cambridge University Press. 2015.
Last updated 2017-09-23

results matching ""

    No results matching ""