Iron Poisoning

DESCRIPTION

Iron toxicity depends on the amount of elemental iron ingested, although tolerable and lethal concentrations can vary between people.
Doses of elemental iron:
- <20 mg/kg are generally not symptomatic.
- 20 to 60 mg/kg are variably symptomatic.
- >60 mg/kg are severely toxic and potentially fatal.
In 2020, a 14-month-old child died due to iron toxicity after ingestion of ferrous sulfate tablets with a reported level of >2,000 mcg/dL.

Pediatric iron exposures are decreasing, likely due to increased awareness and public health efforts; however, iron exposures can be toxic, and poisoning fatalities continue to occur.
Iron ingestions can be divided into unintentional exposures (generally in younger children) and intentional exposures (more common in adolescents).
Incidence: >9,000 iron exposures per year in children <6 years old in the United States (2020)
Many factors contribute to the incidence of iron ingestion:
- Adult multivitamins contain more iron than children’s chewable vitamins.
- Prenatal vitamins contain the highest amount of elemental iron per tablet—up to 100 mg.
- Vitamins and iron tablets can be colorful and resemble candy, making them appealing to young children.
- Caregivers often fail to appreciate the danger of overdose from vitamins with iron and pure iron preparations.
Overall exposures and deaths from iron toxicity have downtrended in the pediatric age range.

Birth of a sibling: up to 1 year after birth, due to increased availability of prenatal vitamins
Age: Among unintentional ingestion, almost all serious mortality and morbidity are in children <5 years of age with ingestion of adult iron formulations.

Parental education: Keep all medications and vitamins away and 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.
The U.S. 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 stages of iron poisoning:
- Stage I (GI phase)
  - Occurs up to 6 hours postingestion
  - 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
  - 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 postingestion
  - Gastric injury may result in strictures, leading to vomiting and potentially gastric outlet obstruction.
Not all patients will present with every stage, and timing of each stage can vary between patients.