Iron Toxicity in Emergency Medicine
- Author: Clifford S Spanierman, MD; Chief Editor: Asim Tarabar, MD more...
Background
Iron overdose has been one of the leading causes of death caused by toxicological agents in children younger than 6 years. Iron is used as a pediatric or prenatal vitamin supplement and for treatment of anemia. Iron is particularly tempting to young children because it appears similar to candy. Patients with anemias that require frequent blood transfusions also are at risk for developing chronic iron toxicity.
Iron overload may develop chronically as well, especially in patients requiring multiple transfusions of red blood cells. This condition develops in patients with sickle cell disease, thalassemia, and myelodysplastic syndromes.
Pathophysiology
Iron toxicity can be classified as corrosive or cellular.
- Corrosive toxicity: Iron is an extremely corrosive substance to the GI tract. It acts on the mucosal tissues and can manifest with nausea, vomiting, abdominal pain, hematemesis, and diarrhea; patients may become hypovolemic because of significant fluid and blood loss.
- Cellular toxicity: The absorption of excessive quantities of ingested iron results in systemic iron toxicity. Severe overdose causes impaired oxidative phosphorylation and mitochondrial dysfunction, which can result in cellular death. The liver is one of the organs most affected by iron toxicity, but other organs such as the heart, kidneys, lungs, and the hematologic systems also may be impaired.
- End result of corrosive and cellular toxicity is significant metabolic acidosis due to several factors.
- Hypoperfusion due to significant volume loss, vasodilatation, and negative inotropic effect of iron will result in lactic acidosis.
- Inhibition of oxidative phosphorylation will promote anaerobic metabolism.
Individuals demonstrate signs of GI toxicity after ingestion of more than 20 mg/kg. Moderate intoxication occurs when ingestion of elemental iron exceeds 40 mg/kg. Ingestions exceeding 60 mg/kg can cause severe toxicity and may be lethal.
Suggested doses are based on calculation of the amount of elemental iron. Different iron preparations (salts) contain different amounts of elemental iron.
- Fumarate - 33%
- Sulfate - 20%
- Gluconate - 12%
Chronic iron overload may deposit iron into organs such as the liver and heart, which may cause death due to myocardial siderosis.
Epidemiology
Frequency
United States
More than 20,000 children accidentally ingested iron in 1995.[1] Iron was the most common cause of childhood mortality due to nonintentional ingestion. The incidence of iron poisoning has decreased dramatically.
Mortality/Morbidity
Iron poisoning may result in mortality or short-term and long-term morbidity.
Sex
Pregnant patients are at increased risk due to availability of prenatal vitamins and iron supplements in addition to the emotional stress that pregnancy can precipitate.
Age
Iron overdose is one of the leading causes of fatality from toxicological agents in children younger than 6 years.
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