Iron Poisoning

Iron Poisoning is a topic covered in the 5-Minute Pediatric Consult.

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Basics

Description

  • Iron poisoning is a common and potentially fatal ingestion.
  • Toxicity depends on the amount of elemental iron ingested, although tolerable and lethal concentrations are not firmly established.
  • Doses of <20 mg/kg of elemental iron are generally not symptomatic, of 20 to 60 mg/kg are variably symptomatic, and of >60 mg/kg are severely toxic and potentially fatal.

Epidemiology

  • Accounts for about 2–4% of all exposures in children and adolescents
  • Can be divided into unintentional (younger children) and intentional (adolescents)
  • Incidence: almost 11,000 iron exposures per year in children <6 years old in United States, based on the 2015 American Association of Poison Control Centers Annual Report
  • Many factors contribute to the incidence of iron ingestion:
    • High-iron preparations such as prenatal vitamins are readily available (prenatal vitamins contain the highest amount of iron per tablet).
    • Many preparations are attractive and candy-like.
    • Caregivers often fail to appreciate the danger of overdose from vitamins and pure iron preparations.
  • Although vitamin ingestions are increasing, the incidence of fatal iron ingestions has declined since the 1990s, perhaps due to changes in package labels and child-resistant packaging.

Risk Factors

  • Birth of a sibling, including up to 1 year after (increased availability of prenatal vitamins)
  • Among unintentional ingestion, almost all serious mortality and morbidity is in children <5 years of age (ingestion of adult iron formulations).

General Prevention

  • Parental education: Keep all medications and vitamins out of reach in child-resistant packaging.
  • In 1997, federal regulations required unit-dose packaging (blister packs) for all iron preparations with >30 mg of elemental iron per dose.
  • Significant decrease in iron ingestion–related deaths after regulations
  • The United States Food and Drug Administration (FDA) removed regulations in 2003, although many manufacturers voluntarily continue this type of packaging.

Pathophysiology

  • Iron directly damages cells, interfering with aerobic respiration. The primary systems affected by iron are the gastrointestinal (GI) tract, including the liver, and the cardiovascular system.
  • There are five classic stages of iron poisoning:
    • Stage I (GI phase)
      • Occurs up to 6 hours post ingestion
      • Characterized by GI mucosal injury, leading to abdominal pain, vomiting, diarrhea, and GI bleeding (hematemesis or hematochezia)
      • Metabolic acidosis may be present, and death may be caused by capillary leakage and hypovolemic shock.
    • Stage II (latent)
      • 6 to 24 hours after ingestion
      • Relative stability and temporary resolution of GI symptoms
      • Does not always occur
      • Although there may be improvement of symptoms, there is continued cellular toxicity and metabolic acidosis.
    • Stage III (shock)
      • 12 to 24 hours after ingestion (can occur earlier with high dose ingestions)
      • Systemic symptoms: hemodynamic instability, shock, metabolic acidosis
      • Coagulopathy is common and worsens GI bleeding (can occur even without hepatotoxicity).
      • Vasodilation can lead to hypovolemia, and myocardial injury can lead to cardiogenic shock.
    • Stage IV (hepatotoxicity)
      • Within 48 hours after ingestion
      • May result in liver failure
    • Stage V (late)
      • 2 to 8 weeks post ingestion
      • Gastric injury may result in strictures, leading to vomiting and potentially gastric outlet obstruction.

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