Basics
Description
- Iron poisoning is a common and potentially fatal ingestion.
- Toxicity depends on the amount of elemental iron ingested, although tolerable and lethal concentrations are not firmly established.
- Doses of <20 mg/kg of elemental iron are generally not symptomatic, of 20-60 mg/kg are variably symptomatic, and of >60 mg/kg are severe toxic and potentially fatal.
Epidemiology
- Accounts for about 2-4% of all exposures in children and adolescents
- Many factors contribute to the incidence of iron ingestion:
- High-iron preparations such as prenatal vitamins are readily available.
- Many preparations are attractive and candy-like.
- Caregivers often fail to appreciate the danger of overdose from vitamins and pure iron preparations.
- Although vitamin ingestions are increasing, the incidence of fatal iron ingestions has declined since the 1990s, perhaps due to changes in package labels and child-resistant packaging.
Risk Factors
- Birth of a sibling (increased availability of maternal vitamins)
- Among unintentional ingestion, almost all serious mortality and morbidity is in children younger than 5 years of age (ingestion of adult iron formulations).
Pathophysiology
- Iron directly damages cells, interfering with aerobic respiration. The primary systems affected by iron are the gastrointestinal (GI) tract, including the liver, and the cardiovascular system.
- There are five classic stages of iron poisoning:
- Stage I (GI phase)
- Occurs up to 6 hours postingestion
- Characterized by GI mucosal injury, leading to pain, vomiting, diarrhea, and GI bleeding
- Metabolic acidosis may be present, and death may be caused by capillary leakage and hypovolemic shock.
- Stage II (quiescent)
- 6-24 hours after ingestion
- Relative stability and temporary resolution of GI symptoms
- Stage III (recurrence)
- 24-48 hours after ingestion
- Recurrence of GI injury leading to bleeding, shock, and acidosis
- Vasodilation can lead to hypovolemia, and myocardial injury can lead to cardiogenic shock.
- Coagulopathy is common.
- Stage IV (hepatotoxicity)
- Within 48 hours after ingestion
- May result in liver failure
- Stage V (late)
- 2-8 weeks postingestion
- Gastric injury may result in strictures, leading to vomiting and potentially gastric outlet obstruction.
Diagnosis
History
- Witnessed or suspected iron product ingestion
- Determine the amount of elemental iron ingested and the time of ingestion.
- The percentage of elemental iron by iron salt is ferrous fumarate, 33%; ferrous chloride, 28%; ferrous sulfate, 20%; and ferrous gluconate, 12%.
Physical Exam
- Evaluate for poor perfusion: hypotension, decreased capillary refill, pallor, tachycardia, and CNS depression (lethargy or coma).
- Evaluate for GI injury: abdominal tenderness and occult or apparent GI bleeding.
- Evaluate for heart injury: distant heart sounds, poor pulses, mottled skin, distended jugular veins, pulmonary edema.
Alert
Strongly consider the diagnosis of acute iron poisoning in a lethargic, hypotensive toddler.
Diagnostic Tests & Interpretation
Lab
Initial Lab Tests
- Blood gas
- Complete blood count
- Glucose, liver function, and coagulation studies
- Renal function
- Electrolytes
Imaging
- Abdominal radiograph
- May reveal iron pills. The absence of findings does not exclude iron toxicity (liquid preparations and multivitamins are not radiopaque).
- GI decontamination may be recommended if undissolved tablets are confirmed.
Diagnostic Procedures/Other
- Serum iron level
- Measure on presentation and every 1-2 hours.
- The serum iron level peaks at 4-6 hours postingestion and can help determine the severity of overdose. Iron levels 300-500 mcg/dL: usually mild to moderate GI toxicity; 500-1,000 mcg/dL: serious toxicity; greater than 1,000 mcg/dL: severe and life-threatening toxicity
- Total iron-binding capacity (TIBC) not recommended (may be inaccurate in toxicity)
Differential Diagnosis
- Ingestions
- Methanol
- Propylene glycol
- Ethanol
- Ethylene glycol
- Salicylate
- Toluene
- GI bleeding
- Trauma
- Perforation
- Intussusception
- Gastritis
- Esophageal inflammation or tear
- Vascular malformation
- Other
- Reye syndrome
- Serious bacterial infection: sepsis, meningitis
- Diabetic ketoacidosis
Treatment
General Measures
- Asymptomatic patients after 6 hours of ingestion or ingestions of less than 40 mg/kg elemental iron with mild symptoms can be observed at home.
- Symptomatic patients with persistent or severe GI symptoms, or ingestion with greater than 40 mg/kg elemental iron, should be evaluated in a health care facility.
Special Therapy
- GI decontamination
- Whole-bowel irrigation for patients with a significant number of pills on imaging studies
- Gastric lavage with tap water or normal saline if early after ingestion and suspect a large iron load
- Activated charcoal is not recommended (iron binds poorly).
- Syrup of ipecac is not recommended.
- Rarely, endoscopy or gastrotomy may need to be performed to remove embedded pills.
- Iron chelation with deferoxamine
- Deferoxamine binds with free iron and is excreted by the kidneys. It is indicated if systemic signs of toxicity or peak iron concentration is greater than 500 mcg/dL.
- Administered parenterally via continuous infusion at 15 mg/kg/h. (Consultation with a specialist or regional poison control center is recommended.)
- Chelation can be discontinued with clinical improvement and resolution of metabolic acidosis.
- Side effects of chelation include hypotension and acute respiratory distress.
- Although iron cannot be dialyzed, the ferrioxamine complex after chelation can be, and dialysis may be indicated in the setting of acute renal failure.
Inpatient Considerations
Initial Stabilization
- Evaluate and stabilize shock.
- Intubation should be considered in a lethargic patient to facilitate GI decontamination.
Admission Criteria
- Patients with mild but persistent symptoms after 6 hours or ingestion with greater than 40 mg/kg (recommend consultation with a specialist or poison control center)
- Symptomatic patients with significant toxicity or shock should be treated in an intensive care setting by specialists skilled in management of pediatric ingestions.
Discharge Criteria
Stable hemodynamic status and resolution of metabolic acidosis (recommend consultation with a specialist or poison control center)
Ongoing Care
Follow-up Recommendations
Monitor for possible late complications, such as strictures of the GI tract (can occur up to 2 months postingestion).
Patient Education
Encourage families to secure iron-containing vitamins and supplements out of reach of children.
Prognosis
- Iron ingestions rarely result in serious injury.
- Shock and ingestion of elemental iron greater than 1,000 mcg/dL associated with mortality
Complications
- GI and hepatic infarction and necrosis
- Gastric or intestinal scarring and strictures
- Metabolic acidosis
- Shock (hypovolemic, hemorrhagic, cardiogenic)
- Coagulopathy
- Pulmonary edema
- Yersinia enterocolitica infection or sepsis (Chelation can encourage bacterial growth.)
- Death
Additional Reading
- Fine JS. Iron poisoning. Curr Probl Pediatr. 2000;30(3):71-90. [View Abstract]
- Henretig FMl. Acute iron poisoning. In: Shaw LM, Kwong TC, eds. The Clinical Toxicology Laboratory: Contemporary Practice of Poisoning Evaluation. Washington, DC: AACC Press; 2001:401-409.
- Madiwale T, Liebelt E. Iron: not a benign therapeutic drug. Curr Opin Pediatr. 2006;18(2):174-179. [View Abstract]
- Manoguerra AS, Erdman AR, Booze LL, et al. Iron ingestion: an evidence-based consensus guideline for out-of-hospital management. Clin Toxicol. 2005;43(6):553-570. [View Abstract]
- Tenenbein M. Unit-dose packaging of iron supplements and reduction of iron poisoning in young children. Arch Pediatr Adolesc Med. 2005;159(6):557-560. [View Abstract]
Codes
ICD09
- 964.0 Poisoning by iron and its compounds
- 985.8 Toxic effect of other specified metals
ICD10
- T45.4X1A Poisoning by iron and its compounds, accidental, init
- T56.891A Toxic effect of other metals, accidental (unintentional), initial encounter
SNOMED
- 445902007 Poisoning by iron (disorder)
- 216802005 Accidental poisoning by iron compounds (disorder)
FAQ
- Q: Why isn't syrup of ipecac recommended to induce vomiting?
- A: Because the major early signs and symptoms involving the GI tract include vomiting, inducing vomiting may interfere with the clinical assessment. There is also the risk of aspiration in the patient with severe poisoning.
- Q: What is the recommendation regarding observation of a patient for development of symptoms with iron ingestion of an unknown quantity?
- A: Observe for 6 hours. Those who are asymptomatic 6 hours after ingestion are not likely to exhibit systemic illness.
- Q: What is the recommendation regarding nonintentional ingestion of children's vitamins with iron, carbonyl iron formulations, or polysaccharide iron complex formulations?
- A: These ingestions are generally deemed to contain low levels of iron, and the American Association of Poison Control Centers recommends against emergency room referral for nonacute patients with adequate home supervision. Even patients with mild diarrhea and emesis can be safely observed in the home following these ingestions, although consultation with a physician and poison control hotline is still advised.