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 women; approximately 3 grams is lethal for a two-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.
The amount of iron ingested may give a clue to potential toxicity. The therapeutic dose for iron deficiency anemia is 3–6 mg/kg/day. Toxic effects begin to occur at doses above 10–20 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 heptahydrate has 65 mg (20%) of elemental iron
- A 325-mg tablet of ferrous gluconate has 39 mg (12%) of elemental iron
- A 325-mg tablet of ferrous fumarate has 107.25 mg (33%) of elemental iron
- 200 mg ferrous sulfate, dried, has 65 mg (33%) of elemental iron
Signs and symptoms
The first indication of iron poisoning by ingestion is 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 for a prolonged period of time, symptoms are likely to be similar to other causes of iron overload.
Footnotes and references
- Valentine, Kevin; Mastropietro, Christopher; Sarnaik, Ashok P. "Infantile iron poisoning: Challenges in diagnosis and management". Pediatric Critical Care Medicine. 10 (3): e31–e33. doi:10.1097/pcc.0b013e318198b0c2.
- "Iron Toxicity, What You Don't Know". Plants Poisonous to Livestock. Cornell University Department of Animal Science. Retrieved 2012-04-09.
- Tenenbein, M. (June 2005). "Unit-Dose Packaging of Iron Supplements and Reduction of Iron Poisoning in Young Children". Arch Pediatr Adolesc Med. 159: 557–560. doi:10.1001/archpedi.159.6.557. PMID 15939855.
- "AAPCC Annual Reports". American Association of Poison Control Centers.
- Stoltzfus RJ, Dreyfuss ML (2000). "Guidelines for the Use of Iron Supplements to Prevent and Treat Iron Deficiency Anemia" (PDF). International Nutritional Anemia Consultative Group, International Life Sciences Institute Press.
- Allen LH (April 2002). "Iron Supplements: Scientific Issues Concerning Efficacy and Implications for Research and Programs". J. Nutr. 132 (4): 813S–9S. PMID 11925487.
- "What Is Anemia?". National Heart, Lung, and Blood Institute, U.S. Dept. of Health and Human Services. 18 May 2012.
- "Hemochromatosis and Anemia Diet". Iron Overload Diseases Association.
- "Iron Poisoning". Webmd.com. Retrieved 2012-04-09.
- "Iron Tests". The Free Dictionary by Falex. citing: Gale Encyclopedia of Medicine. Copyright 2008
- "Iron poisoning". General Practice Notebook.
- "Iron Poisoning". WebMD.
- O’Malley, Gerald F.; O’Malley, Rika. "Iron Poisoning". Poisoning, Injuries and Poisoning, Merck Manual Home Edition. Merck Sharp & Dohme. on merckmanuals]