A two-year-old boy was brought to the emergency department because of vomiting. About 30 minutes prior, he was found by his parents with an open bottle containing ferrous fumarate tablets. The mother estimates about five tablets are missing, and each tablet contains 65 mg of elemental iron. The boy had three episodes of non-bloody vomiting. The physical examination is essentially normal except for tachycardia. Which of the following is the next best step?
get serum iron level four hours after ingestion
The patient has symptoms and a history compatible with iron toxicity. The severity of an exposure is related to the amount of elemental iron ingested. Ferrous sulfate contains 20 percent elemental iron, ferrous gluconate has 12 percent, and ferrous fumarate contains 33 percent. Iron is directly corrosive to the GI mucosa, which can lead to hematemesis, melena, ulceration, infarction, and potential perforation. For significant ingestions (> 20 mg/kg of elemental iron), especially when tablets are identified on the abdominal radiograph, whole-bowel irrigation with a polyethylene glycol electrolyte lavage solution (PEG-ELS) is routinely recommended. Iron toxicity is described in four stages. The initial stage, 30 minutes to six hours after ingestion consists of profuse vomiting and diarrhea, abdominal pain, and significant volume losses, leading to potential hypovolemic shock. The second stage, six to 24 hours after ingestion, is the quiescent phase where GI symptoms typically resolve. In the third stage, occurring 12 to 24 hours after ingestion, patients develop multi-system organ failure, shock, hepatic and cardiac dysfunction, acute lung injury, and profound metabolic acidosis. Symptomatic patients and patients with a large exposure by history should have serum iron levels drawn four to six hours after ingestion. Serum iron concentrations of < 500 µg/dL four to eight hours after ingestion suggest a low risk of significant toxicity, whereas concentrations of > 500 µg/dL indicate significant toxicity.
