In the fourth stage taking place 12 to 96 hours after ingestion, liver toxicity and failure occurs as the cells begin to die. In the last stage of iron poisoning following 2 to 8 weeks after ingestion, scarring of the gastrointestinal mucosal lining resulting in bowel obstruction. Cause
Pathophysiology
Iron is essential for the production of hemoglobin in red blood cells which is responsible for transporting oxygen throughout the body. In normal physiologic conditions, nonionic forms of iron (Fe°) are converted into ferrous iron (Fe2+) by gastric acid in the stomach. Ferrous iron is then absorbed in the small intestine where it is oxidized into its ferric iron (Fe3+) form before being released into the bloodstream. Free iron in the blood is toxic to the body as it disrupts normal cell function, damaging organs such as the liver, stomach, and cardiovascular system. The human body has protective mechanisms in place to prevent excess free ferric iron from circulating the body. When being transported throughout the body, iron is bound to an iron transporting protein called transferrin to prevent iron from being absorbed into different cells. Any excess iron is stored as ferritin in the liver. In the event of iron overdose, iron stores become oversaturated and the bodys protective mechanisms fail resulting in excess free circulating iron. Toxic Dose
Iron poisoning can occur when doses of 20 to 60 mg/kg or more of elemental iron is ingested with most cases reporting primarily gastrointestinal symptoms. Systemic signs and symptoms shown in serious toxicity occur at higher doses exceeding 60 mg/kg.
It is a chelating agent and binds to free iron in the body in order to be eliminated by the kidneys into urine. Dosing of deferoxamine should be determined through consultation with a toxicologist but is typically continuously infused at 15 mg/kg to 35 mg/kg per hour and not exceeding the maximum daily dose of 6 grams for adults. In pediatric patients, doses should not exceed 15 mg/kg per hour. recommended duration of treatment is until symptoms have resolved which is usually 24 hours. In non-fatal cases of iron poisoning where there is liver failure, liver transplantation may be necessary.Treatment of iron poisoning should be based on clinical presentation, peak serum iron levels and other laboratory results. As a general guideline, patients who have ingested lower doses of elemental iron, have a peak serum iron level less than 500mcg/dL and are asymptomatic or only exhibit mild gastrointestinal symptoms typically do not require treatment and should be monitored for 6 hours after ingestion. In cases where high doses of elemental iron have been ingested and the patient is exhibiting signs and symptoms of severe systemic iron poisoning, supportive care measures like volume resuscitation and deferoxamine should be initiated immediately. A quick response to iron poisoning can significantly improve clinical outcomes. See also
Overnutrition
Iron overload

References
External links
Iron poisoning in General Practice Notebook
Iron Poisoning at WebMD
Iron Poisoning Merck Manual