Poisoning - Iron

Disclaimer

These guidelines have been produced to guide clinical decision making for the medical, nursing and allied health staff of Perth Children’s Hospital. They are not strict protocols, and they do not replace the judgement of a senior clinician. Clinical common-sense should be applied at all times. These clinical guidelines should never be relied on as a substitute for proper assessment with respect to the particular circumstances of each case and the needs of each patient. Clinicians should also consider the local skill level available and their local area policies before following any guideline. 

Read the full PCH Emergency Department disclaimer.

Aim 

To guide PCH ED staff with the assessment and management of iron poisoning in children.

This is a general approach to iron poisoning - for specific details, please contact Poisons Information: 13 11 26 or refer to Poisoning Overview ED guideline.

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 13 11 26).

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%

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)

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 days
  • Abdominal pain
  • Vomiting
  • Gastrointestinal fibrosis/strictures
  • Cirrhotic liver disease

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
20-40/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 elemental iron 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 elemental 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.

Bibliography

  1. Murray L, Little M, Pascu O, Hogget K. (2015) Toxicology Handbook, 3rd Edition, Churchill Livingstone Australia
  2. Poisons Information Service 131126
  3. AMH Children's Dosing Companion (online). Adelaide: Australian Medicines Handbook Pty Ltd; 2015 January. Available from: http://childrens.amh.net.au
  4. Australian Medicines Handbook (online). Adelaide: Australian Medicines Handbook Pty Ltd; 2015 January. Available from: http://amhonline.amh.net.au
  5. Toxinz Poisons Information (2013) National Poisons Centre, New Zealand. Online – http://www.toxinz.com

Endorsed by:  Director, Emergency Department  Date:  May 2018


 Review date:   May 2021


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