Harvey's Garden

Acute iron poisoning

2 min read

  • Etiology/Pathophysiology
    • Ingestion of toxic doses of elemental iron (e.g., ferrous sulfate tablets), often in children (accidental) or as a suicide attempt in adults.
    • Cellular Toxicity: Free iron is directly toxic. It generates free radicals via the Fenton reaction, leading to lipid peroxidation and damage to cellular mitochondria. This uncouples oxidative phosphorylation, shifting cells to anaerobic metabolism and causing profound lactic acidosis.
    • Corrosive Effects: Iron has a direct caustic effect on the GI mucosa, leading to hemorrhagic gastroenteritis, fluid loss, and potential perforation.
    • Systemic Effects: Shock results from a combination of hypovolemia (from GI losses) and vasodilation. The liver is a primary target, leading to hepatotoxicity.
  • Clinical Features (5 Classic Stages)
    • Stage 1 (0-6 hours): GI Phase.
      • Abdominal pain, vomiting (often bloody), diarrhea (can be bloody), hematemesis, melena.
      • Can lead to hypovolemic shock.
    • Stage 2 (6-24 hours): Latent Phase.
      • Apparent clinical improvement as GI symptoms resolve. This is a deceptive phase where iron is absorbed and distributed to tissues.
    • Stage 3 (12-72 hours): Shock & Metabolic Acidosis.
      • Recurrence of symptoms with systemic toxicity.
      • Profound anion gap metabolic acidosis.
      • Shock (cardiogenic/distributive), poor perfusion, altered mental status, coma.
    • Stage 4 (12-96 hours): Hepatotoxicity.
      • Fulminant hepatic failure with jaundice, coagulopathy, and hypoglycemia.
    • Stage 5 (2-8 weeks): Bowel Obstruction.
      • Gastric outlet obstruction or intestinal strictures due to scarring from the initial corrosive injury.
  • Diagnostics
    • Labs:
      • Serum Iron Level: Peak level drawn 4-6 hours post-ingestion is key.
        • &gt 350 mcg/dL: Associated with toxicity.
        • &gt 500 mcg/dL: Associated with severe toxicity.
      • Anion Gap Metabolic Acidosis: A hallmark of severe poisoning.
      • ↑ Glucose, ↑ WBC count (>15,000) are associated with significant ingestions.
      • Monitor LFTs, coagulation studies, and electrolytes.
    • Imaging:
      • Abdominal X-ray (KUB): Can be useful to visualize radiopaque iron tablets, confirming ingestion and guiding decontamination. However, a negative AXR does not rule out ingestion (chewable/liquid forms are not radiopaque).
  • Treatment
    • Supportive Care: ABCs, aggressive IV fluid resuscitation for shock.
    • Decontamination:
      • Whole Bowel Irrigation (WBI): Consider for large ingestions if tablets are visible on X-ray. Performed with polyethylene glycol via NG tube.
      • Activated charcoal is NOT effective as it does not bind iron.
    • Antidote: Deferoxamine
      • A chelating agent that binds free iron to form ferrioxamine, which is renally excreted.
      • Indications: Severe symptoms such as shock, altered mental status, severe metabolic acidosis, OR a serum iron level >500 mcg/dL.
      • Excretion of the ferrioxamine complex classically turns the urine a “vin rosé” (reddish-pink) color.

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