- When calculating the amount of iron ingested, one must convert to elemental content. More than 40 mg/kg is associated with significant toxicity and more than 60 mg/kg with death.
- Phase II of iron toxicity is the quiescent or danger phase of the overdose. The patient will appear to be better clinically, which may falsely reassure the clinician.
- Serum iron concentrations should be obtained between 2 and 6 hours after ingestion.
- The “vin rose” urine occurs after deferoxamine treatment. It represents the ferrioxamine complex being excreted in the urine.
- Whole bowel irrigation should be considered if multiple radiopaque iron tablets are seen on abdominal radiography.
- The preferred route of deferoxamine administration is intravenously at a rate of 15 mg/kg/h.
Iron is one of the most important pediatric toxins. It is an extremely common cause of poisoning and has a high potential for morbidity and mortality. According to data from the American Association of Poison Control Centers (AAPCC), from 1983 through 1990 iron was the most common cause of pediatric unintentional ingestion death, accounting for 30.2% of reported cases.1 From 1985 through 1989, there were more than 11 000 reported exposures to iron in children.
The FDA has required unit dose packaging (blister-packs) for most products containing more than 30 mg elemental iron per tablet. Since this change in packaging the rate of serious iron ingestions reported has plummeted. In 2006, only 3953 iron ingestions were reported to the AAPCC. There were no fatalities.2 This change in packaging has had a tremendous effect in saving lives.
Iron is absorbed through the gastrointestinal mucosa in the ferrous (Fe2+) state. It is oxidized to the ferric (Fe3+) state and is bound to transferrin. Toxicity occurs when the transferrin-binding capacity is exceeded. Iron is a potent catalyst of free radical generation, which is the chief mechanism of iron toxicity. Circulating free iron can damage blood vessels and can cause transudation of fluids from the intravascular space, resulting in hypotension. Hypotension is potentiated by the release of ferritin, a potent vasodilator. Other target organs include the gastrointestinal tract, heart, and lungs. Autopsy findings include cloudy swelling, fatty degeneration, and necrosis of hepatocytes. Iron deposits can be found in hepatocytes and the reticuloendothelial cells of the liver and spleen. Fatty degeneration occurs in the heart and renal tubules. The lungs may reveal congestive changes.
It is important to identify the specific preparation because the content of elemental iron varies (Table 127–1). If the preparation and the number of tablets are known, the total dose of elemental iron can be calculated. A dose exceeding 60 mg of elemental iron per kilogram of body weight is associated with life-threatening toxicity. Table 127–2 reflects poison center-based triage guidelines.
Table 127-1. Iron Preparations