Tasty Morsels of EM 127 – #FRCEM Iron Toxicity

24 Aug

I’m entering a few months prep for the UK and Ireland exit exam in Emergency Medicine: the FRCEM. I’ll be adding lots of little notes on pearls I’ve learned along the way. A lot of my revision is based around the Handbook of EM as a curriculum guide and review of contemporary, mainly UK guidelines. I also focus on the areas that I’m a bit sketchy on. With that in mind I hope they’re useful.

You can find more things on the FRCEM on this site here.

Again, never had to give the DFO so worth putting on here.

What is the physiology in iron poisoning?

  • iron is a tad toxic in its unbound state therefore your body keeps good control of it by having it bound to a protein like transferrin. You can measure something called total iron binding capacity if you wish
  • in OD the binding ability of the body is overwhelmed
  • this results in free Iron ions floating around the blood stream causing an anion gap acidosis, coma, seizures, liver injury etc…
  • note that the raised anion gap met acidosis is caused by iron uncoupling oxidative phosphorylation. Iron is a cation not an anion so if anything you’d expect it to lower the anion gap but it doesn’t do that. Lithium OD is apparently the one that causes a low anion gap.
  • the tablets themselves also cause direct caustic injury to the gut mucosa resulting in bleeding and long term strictures etc…
  • the key in assessing the toxicity is looking at the elemental iron as the different preparations all differ on this you’ll have to check the specific preparation. You can count the tablets on an AXR so at least you can get a reasonable idea of how many tablets were taken
  • 60mg/kg elemental iron is the cut off for bad things.

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How does it present?

  • tummy pain
  • vomiting
  • diarrhoea
  • high sugars and WCC common
  • in the severe poisonings expect met acidosis, coma and shock.
  • GI bleeding is considered a sign of severe poisoning

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How do we manage it?

  • WBI as a recommended option
  • send a level at 4 hrs and this is a reasonable predictor of severity
  • give desferroxamine
    • 15mg/kg/hr till better (I paraphrase…)
    • works by chelating iron. turns the wee wee a funny reddy orange

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