EM · Toxicology and environmental emergencies

Iron poisoning

Also known as Iron toxicity · Ferrous sulphate overdose · Acute iron ingestion · Elemental iron poisoning · Desferrioxamine-responsive iron overdose

Iron poisoning — the heavy-metal overdose whose lethality rides on a single pharmacological concept: the body has no excretory route for free iron, so any dose that overwhelms transferrin's binding capacity releases catalytic free iron that drives free-radical lipid peroxidation of mitochondrial membranes. The clinical course unfolds in five stereotyped stages the Fellowship candidate must recite: gastrointestinal (nausea, vomiting, haematemesis, diarrhoea, 0 to 6 hours), quiescent (apparent recovery, 6 to 24 hours — the lethal trap), shock (distributive shock with capillary leak and metabolic acidosis, 12 to 24 hours), hepatotoxicity (centrilobular necrosis from mitochondrial free-radical injury, 1 to 3 days), and gastrointestinal obstruction (corrosive scarring with pyloric or intestinal stricture, 2 to 6 weeks). The serum iron level drawn at 4 to 6 hours drives treatment: desferrioxamine 15 mg per kg per hour intravenous chelation for any symptomatic patient or a level over 350 mcg per dL (60 micromol per L), continued until the patient is clinically well and the level is falling. Whole bowel irrigation with polyethylene glycol is the decontamination of choice for enteric-coated or sustained-release tablets and for a radio-opaque pill mass on abdominal X-ray; activated charcoal does not adsorb iron and has no role. The differential is other heavy metals (lead, arsenic) and the tricyclic antidepressant overdose (wide QRS). ACEM-primary, globally tagged.