Iron poisoning


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    This guideline has been adapted for statewide use with the support of the Victorian Paediatric Clinical Network

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    Key Points

    1. In iron poisoning, the amount of elemental iron ingested determines the risk, not the amount of iron salt.
    2. In severe poisonings, often there is a period of latency where symptoms subside before organ failure occurs.
    3. Abdominal X-ray may be helpful if tablets have been ingested
    4. Consult a toxicologist when considering administering desferrioxamine.

    For 24 hour advice, contact Victorian Poisons Information Centre 131126

    Background

    Iron supplements are available in several different formulations. In iron poisoning, the important consideration is the amount of elemental iron ingested, not the amount of iron salt.
    Table: Iron Medications

    Product

    per tablet

    Elemental iron per tablet

    FGF

    250mg sulphate

    80mg

    Fefol

    270mg sulphate

    87.4mg

    Ferrogradumet

    325mg sulphate

    105mg

    Ferro-tab

    200mg fumarate

    65.7mg

    Iron Melts

    25.4mg fumarate

    5mg

    Ferro-Liquid

    30mg/mL sulphate

    6mg/mL

    Percentage elemental iron:

    Ferrous fumarate 33%, ferrous chloride 28%, ferrous sulphate 20%, ferrous gluconate 12%
    Iron is also found in some plant fertilisers, e.g. sulphate of iron, and in some snail baits, e.g. iron phosphate.

    Assessment

    Patients Requiring Assessment

      • Ingestion of > 40mg/kg elemental iron.
      • Ingestion of an unknown quantity.
      • Any symptomatic children.

    History and Examination
    Initial symptoms:

      • Nausea, vomiting, diarrhoea, abdominal pain, hypotension, haematemesis, fever
      • Gastrointestinal symptoms related to the corrosive nature of iron may occur without systemic toxicity
      • Lack of symptoms within the first 6 hours makes significant toxicity unlikely.

    Latent period:

      • In severe iron poisoning, there is often 6-24 hour latent period when initial symptoms resolve, before overt systemic toxicity declares.

    Other symptoms:

      • Usually appear at 6-24 hours and last 12-24 hours
      • CVS: Tachycardia, vasoconstriction, hypotension and shock
      • Metabolic: metabolic acidosis
      • These are related to fluid shifts from intravascular to extravascular compartments and cellular hypoxia

    Multiple organ failure:

      • Occurs >48 hours after ingestion
      • Particularly hepatic failure

    Investigations

    Asymptomatic Children:

      • If tablet ingestion
        • Abdominal  x ray (AXR) (if negative, no further investigation or observation are required)
      • If unknown amount or >40 mg/kg ingested
        • Measure serum iron concentrations 4 hourly until falling.

    All symptomatic children should have the following investigations:

      • AXR (if tablet ingestion)
        • AXR may also be helpful in evaluating gastrointestinal decontamination after whole bowel irrigation (WBI)
      • Blood gas (acidosis)
      • Glucose (hyperglycaemia)
      • Serum iron concentration
        • Should be performed immediately and repeated 4-6 hours after ingestion since concentration usually peaks at 4-6 hours after ingestion.
        • Concentrations taken after 4-6 hours may underestimate toxicity because the iron may have either been distributed into tissues or be bound to ferritin.
        • In the case of slow release or enteric coated tablets, concentrations should be repeated at 6-8 hours as absorption may be erratic and delayed.
        • Once desferrioxamine is commenced, iron concentrations are not accurate at most labs using automated methods (including RCH)
      • FBE (leukocytosis)
      • UEC
      • LFTs
      • Clotting (reversible early coagulopathy and late coagulopathy secondary to hepatic injury)
      • Blood group and cross-match

    Acute Management

    Resuscitation

    • Supportive treatment to maintain adequate blood pressure and electrolyte balance is essential.
    • I.V. fluid resuscitation 20 mL/kg for hypovolaemia or hypotension
    • Potassium and glucose administration as necessary.

    Decontamination

    • Activated charcoal does not bind to iron and is not indicated.
    • Decontamination of choice is whole bowel irrigation (WBI)
      • WBI is indicated if the AXR reveals tablets or capsules ingested and more than 60mg/kg ingested
      • Discuss with a toxicologist (131126) for advice before performing WBI
      • Usual protocol is nasogastric colonic lavage solution 30mL/kg/hr until rectal effluent clear.  This is an extremely resource-intensive processing requiring 1-1 nursing.
      • WBI is contraindicated if there are signs of bowel obstruction or haemorrhage

    Ongoing care and monitoring

    Antidote - Desferrioxamine

    • Desferrioxamine is a chelating agent that forms a water soluble desferrioxamine-iron complex
    • Speak to a toxicologist (13 11 26) for advice before administering
    • Consider desferrioxamine if:
      • Serum iron concentrations > 90 micromol/L.
      • Concentration 60 - 90 micromol/L and tablets visible on AXR or symptomatic (nausea, vomiting, diarrhoea, abdominal pain, haematemesis, fever).
      • The child has significant symptoms of altered conscious state, hypotension, tachycardia, tachypnoea, or worsening symptoms irrespective of ingested dose or serum iron concentration.
      • Do not wait for iron concentration if altered conscious state, shock, severe acidosis (pH <7.1), or worsening symptoms. If serum iron concentration is not readily available, a fall in serum bicarbonate concentration is a reasonable surrogate marker of systemic iron poisoning. Commence desferrioxamine without delay, in consultation with a toxicologist.
    • Desferrioxamine dose 
      • 15mg/kg/hr intravenous
      • The rate is reduced after four to six hours so that the total intravenous dose does not exceed 80mg/kg/24 hours.
    • Duration
      • Significant poisoning usually requires administration for 12 -16 hours, however it is recommended to continue desferrioxamine until:
        • The child is asymptomatic
        • Decontamination complete
        • Anion-gap acidosis resolved
        • Serum iron concentration <60 micromol/L
    • Desferrioxamine has been associated with pulmonary toxicity and should be used with caution if indications persist >24 hours
    • Desferrioxamine-iron complex is renally excreted. If oliguria or anuria develop, peritoneal dialysis or haemodialysis may become necessary to remove ferrioxamine.

    When to admit / consult local paediatric team

    • Ingestions of >40mg/kg or unknown quantities.
    • Admission should be considered for all children and young people with an intentional overdose
    • Consult ICU for children being considered for desferrioxamine or with worsening symptoms.

    When to consider transfer to a tertiary centre:

    • Desferrioxamine and/or whole bowel irrigation is required
    • Significantly decreased conscious stage or conscious state not improving as expected.
    • Need for respiratory support

    Consult Contact Victorian Poisons Information Centre 131126 for advice
    For emergency advice and paediatric or neonatal ICU transfers, call the Paediatric Infant Perinatal Emergency Retrieval (PIPER) Service: 1300 137 650.

    Discharge criteria

    • If <40mg/kg ingestion and negative AXR (if tablet ingestion) can discharge if asymptomatic 6 hours post ingestion
    • If ingestion of >40mg/kg, discharge only if remains asymptomatic and serum iron concentration falling and <60micromol/L on two measurements 4 hours apart
    • Remember in severe iron poisoning, there is often 6-24 hour latent period when initial symptoms resolve, before overt systemic toxicity declares. Thus improvement over this time may be a result of actual improvement or be proceeding deterioration.

    Discharge information and follow-up:

    Poisoning prevention for children Parent information

    Victorian Poisons Information Centre: 13 11 26 www.austin.org.au/poisons
    Intentional self –harm: Referral to local mental health services e.g. Orygen Youth Health: 1800 888 320 
    Recreational poisoning: Referral to YoDAA, Victoria's Youth Drug and Alcohol Advice service: 1800 458 685

     

    Last updated December 2017