Iron Poisoning

Basics

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.

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.

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).

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.

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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