Iron poisoning is an iron overload caused by a large excess of iron intake and usually refers to an acute overload rather than a gradual one. The term has been primarily associated with young children who consumed large quantities of iron supplement pills, which resemble sweets and are widely used, including by pregnant womenâ€"see overnutrition (approximately 3 grams is lethal for a 2 year old). Targeted packaging restrictions in the US for supplement containers with over 250 mg elemental iron have existed since 1978, and recommendations for unit packaging have reduced the several iron poisoning fatalities per year to almost zero since 1998. No known cases of iron poisoning have been identified that are associated with iron mining.
Nature of iron
In nature, iron is usually found in its oxidized form, iron (III) oxide, which is insoluble. Ferrous iron is soluble and its toxicity varies, largely with the integrity of the gastrointestinal lining. Iron supplements are typically used to treat anemia. Modalities include: diet, parasite control, vitamin A, riboflavin (B2), vitamin C (for absorption), folate(B9), vitamin B12 and multivitamin-multimineral supplements, with or without iron; potentially avoiding the use of iron only supplements.
Toxic dosage
The amount of iron ingested may give a clue to potential toxicity. The therapeutic dose for iron deficiency anemia is 3â€"6 mg/kg/day. Toxic effects begin to occur at doses above 10â€"20 mg/kg of elemental iron. Ingestions of more than 50 mg/kg of elemental iron are associated with severe toxicity.
- A 325-mg tablet of ferrous sulfate has 65Â mg (20%) of elemental iron
- A 325-mg tablet of ferrous gluconate has 39Â mg (12%) of elemental iron
- A 325-mg tablet of ferrous fumarate has 107.25Â mg (33%) of elemental iron
In terms of blood values, iron levels above 350-500 µg/dL are considered toxic, and levels over 1000 µg/dL indicate severe iron poisoning.
Signs and symptoms
The first indication of iron poisoning by ingestion is a stomach pain, as iron is corrosive to the lining of the gastrointestinal tract including the stomach. Nausea and vomiting are also common symptoms and bloody vomiting may occur. The pain then abates for 24 hours as the iron passes deeper into the body resulting in metabolic acidosis, which in turn damages internal organs, particularly the brain and the liver. Iron poisoning can cause hypovolemic shock due to iron's potent ability to dilate the blood vessels. Death may occur from liver failure.
If intake of iron is during a prolonged period of time, symptoms are likely similar to other causes of iron overload.
Treatment
Later stage treatment consists of cleaning the iron from the blood, using a chelating agent such as deferoxamine. If this fails then dialysis is the next step.
Footnotes and references
External links
- General Practice Notebook
- Iron Poisoning on WebMD
- Iron Poisoning on merckmanuals
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