Paediatric Acute care Guidelines PMH Emergency Department

This is a general approach to iron poisoning – for specific details, please contact Poisons Information: 131126 or refer to the Toxicology Handbook

Background

Accidental iron ingestion is common in children but severe iron toxicity requiring chelation is rare. 

Iron causes two major effects:

Local – Gastrointestinal irritation

  • Abdominal pain
  • Nausea and vomiting

Systemic – Cellular toxicity causing multi-organ failure 

  • Systemic toxicity may occur with doses greater than 60 mg/kg and is life-threatening with doses greater than 120 mg/kg

General 

Severe iron toxicity is classically described in five stages, although in reality, clinical manifestations of significant iron intoxication do not occur as distinct stages but as a clinical continuum.

Risk Assessment

  • Vomiting and abdominal pain are common even after doses that are not associated with systemic toxicity
  • Systemic iron toxicity is characterised by: 
    • Shock
    • Acidosis
    • Hepatocellular injury
    • Renal injury
  • Risk assessment is based on the potential dose of elemental iron ingested and the evolving clinical features observed 
  • The amount of elemental iron varies according to the form of iron, see Elemental Iron Equivalents table for common iron formulations
    • In Australia the packaging usually states the elemental iron content (thus conversion is not required)
  • If in doubt, consult with the Poisons Information Centre (Telephone 131126)
Elemental Iron Equivalents
Iron Formulation Percentage of Elemental Iron
Ferrous sulphate  20%
Ferrous gluconate 12%
Ferrous fumarate 33%
Ferrous lactate 19%
Ferrous chloride 28%
Ferrous ferrocholinate 13%

Typical Clinical Course

  • Symptoms are dose-dependent  and range from mild GI upset to multi-organ failure
  • Significant toxicity follows predictable course with five clinical phases over time
Phase  Onset Post Ingestion/Duration   Clinical Features 
Phase 1 – Gastrointestinal 0.5-6 hours
  • Abdominal pain
  • Vomiting
  • Diarrhoea 
Phase 2 – Quiescent 6-12 hours
  • Progressive increase in iron absorption and distribution
  • Improvement of gastrointestinal symptoms (sense of recovery)
Phase 3 – Cardiogenic Shock and Acidosis 24-48 hours
  • Hypotension
  • Anion gap metabolic acidosis
  • Shock (may develop from Phase 1)
  • Potential multi-system failure
  • Coma
Phase 4 – Hepatic Necrosis 2-5 days
  • Acute hepatic failure
  • Jaundice
  • Coagulopathy
  • Hypoglycaemia
  • Coma
Phase 5 – Bowel Obstruction  2-6 weeks
  • Abdominal pain
  • Vomiting
  • Gastrointestinal fibrosis/strictures
  • Cirrhotic liver disease 

Investigations 

Screening (in deliberate overdose)

  • 12 lead ECG
  • Blood glucose level
  • Paracetamol level

Specific: 

  • Abdominal X-Ray (quantity and confirmation of ingestion)
  • Iron level at 4-6 hours post ingestion
  • Blood gas
    • Bicarbonate is an indicator for metabolic acidosis (this may be used as a surrogate marker if iron levels are not available)

Management 

  • Priority is the restoration and ongoing replacement of adequate circulatory volume
  • All patients with deliberate self poisoning, regardless of the dose, should be referred to hospital for evaluation 
Ingested dose of Elemental Iron Symptoms and Management
< 20mg/kg

Patients usually remain asymptomatic

Do not require decontamination or referral to hospital

20-40mg/kg

Patients often have mild GI irritation manifested by transient abdominal discomfort and vomiting. One or two vomits are common and symptoms usually last less than 6 hours.

Gastrointestinal decontamination is not required and minimally symptomatic patients (e.g. one or two vomits) do not require referral to hospital

40-60mg/kg

Patients often have abdominal discomfort and vomiting but systemic toxicity is not expected. Symptoms usually resolve within 8 hours.

Symptomatic patients will require referral to hospital for abdominal X-Ray (to confirm that the dose is not larger) and general supportive measures (intravenous fluids may be required)

Systemic toxicity is not expected and admission is usually not required

> 60mg/kg

Patients have severe gastrointestinal symptoms and systemic toxicity may occur.

Patients should be referred to hospital for evaluation and management 

With appropriate management (which may include whole bowel irrigation +/- chelation) admission for greater than 24 hours is uncommon

> 100mg/kg

Patient develop severe gastrointestinal symptoms and systemic toxicity that is potentially lethal.

Early aggressive evaluation, whole bowel irrigation, meticulous fluid resuscitation, chelation and management in an intensive care unit will be required 

Decontamination 

  • Indicated if the risk assessment suggests that the ingested dose is > 60mg/kg, and 
  • Patient has a normal mental status, and 
  • There is evidence of iron tablets within the gastrointestinal tract (radio-opaque tablets are visible on X-Ray, or presentation within 6 hours with clinical evidence of significant ingestion)
  • Activated charcoal does not absorb iron
  • Whole bowel irrigation (WBI) with polyethylene glycol is the treatment of choice 
    • Commence nasogastric infusion at 25mL/kg/hours
    • Consultation with clinical toxicologist is recommended
  • Endoscopic removal may be indicated in patients with a potentially lethal iron ingestion where whole bowel irrigation has failed or is impractical

Antidote

  • Desferrioxamine (chelating agent) is the antidote for systemic iron poisoning
  • The decision to administer desferrioxamine is based on the presence of toxicity (shock, metabolic acidosis, altered mental status) or predicted severe toxicity based on a serum iron level > 90 micromol/L (500 microgram/dL) at 4-6 hours post ingestion. 
  • Clinical Toxicology should be contacted if administration of desferrioxamine is considered. 
  • Specific dosage and administration details should be obtained from the Toxicology Handbook. 

Enhanced Elimination

Not useful

Disposition 

  • Children though to have ingested < 40mg/kg may be managed at home provided they remain asymptomatic.
  • Larger or symptomatic ingestions are evaluated in hospital. The child who remains asymptomatic at 6 hours and has an abdominal X-Ray negative for iron may be safely discharged. 
  • All patients who have deliberately self poisoned with iron are evaluated in hospital. If the history suggests ingestion of < 60 mg/kg of iron and they remain asymptomatic at 6 hours, further medical observation is unnecessary. 
  • Symptomatic patients requiring intravenous fluid therapy or WBI require admission to a medical ward.
  • Those presenting with established systemic iron toxicity or requiring intravenous chelation therapy are admitted to intensive care. 

Nursing

  • Baseline observations include heart rate, respiratory rate, oxygen saturation, blood pressure, pain score and neurological observations
  • Minimum of hourly observations should be recorded whilst in the emergency department
  • Any significant changes should be reported immediately to the medical team
  • A baseline ECG should be performed on arrival
  • Continual cardiac monitoring should be done during desferrioxamine infusion 
  • Fluid balance should be strictly monitored
    • Note the urine may have a red discolouration in the event that chelating agent is given 

References

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