Iron poisoning is often listed in the classic metabolic acidosis mnemonic MUDPILES, but how does it cause an anion gap metabolic acidosis?
HOW? The mechanism appears to be multi-factorial.
Acute excessive ingestion of iron causes direct corrosive damage to the GI tract.
- Free iron penetrates numerous organs such as the liver. It enters hepatocytes, damaging the mitochondria (disrupts oxidative phosphorylation) and increases lipid peroxidation. It also damages microsomes, and other cellular organelles.
- Excessive iron can affect the heart: resulting in fatty necrosis of the myocardium, increased capillary permeability, and a reduction in cardiac output.
- Free iron also stimulates the release of pro-dilatory agents such as serotonin and histamine resulting in hypo perfusion, anaerobic metabolism and lactic acidosis.
- In addition ferrous iron is converted to ferric iron; hydrogen ions are released, adding to the metabolic acidosis.
The profound damage to the liver results in: hypoglycemia, hyperammonemia, coagulation defects,
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