Iron Poisoning

Basics

Description

  • Peak concentrations are 2–4 hr postingestion
  • Serum concentrations not reliable if obtained >4–6 hr after ingestion:
    • Enteric coated or sustained release – warrants serial levels
  • Postabsorption: Iron redistributes into tissues, and fall in serum iron occurs as free iron shifts intracellularly resulting in cellular injury
  • Injury patterns:
    • Corrosive injury to intestinal mucosa may result in profound fluid loss (shock), hemorrhage, and perforation
    • Liver receives largest load of iron because of portal venous circulation – (hemorrhagic periportal necrosis)
  • Free iron:
    • Concentrates in mitochondria, disrupting oxidative phosphorylation; catalyzes lipid peroxidation and free radical formation, resulting in cell death; increases anaerobic metabolism and acidosis
    • Causes myocardial depression, venodilation, and cerebral edema
  • Hydration of ferric form liberates 3 protons, resulting in acidemia

Etiology

Elemental iron ingestion:
  • Nontoxic <20 mg/kg
  • Moderate to severe >40 mg/kg
  • Lethality possible >60 mg/kg
  • Elemental iron equivalents:
    • Ferrous sulfate, 20% (325 mg = 65 mg Fe)
    • Ferrous gluconate, 12%
    • Ferrous fumarate, 33%
  • Prenatal vitamins vary from 60–90 mg elemental iron per tablet
  • Children's vitamins may contain 5–18 mg elemental iron per tablet

Pediatric Considerations
  • Historically notorious for the highest mortality rate among pediatric accidental exposures (adult iron products)
  • Children's chewable iron products have been shown to be safe

There's more to see -- the rest of this topic is available only to subscribers.