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Iron poisoning


  • Statewide logo

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

  • See also

    Poisoning – Acute guidelines for initial management
    Resuscitation

    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 the Poisons Information Centre 13 11 26

    Background

    • Iron preparations are available most commonly in the form of iron salts. The amount of elemental iron in each preparation varies depending upon the salt form.
    • In iron poisoning, the important consideration is the amount of elemental iron ingested, not the amount of iron salt
    • Iron is also found in some plant fertilisers, e.g. sulphate of iron, and in some snail baits, e.g. iron phosphate

    Table: Iron Medications

    Product

    per tablet

    Elemental iron per tablet/capsule

    FGF*

    250 mg ferrous sulphate

    80 mg

    Fefol*

    270 mg ferrous sulphate

    87.4 mg

    Ferrogradumet*, Ferrograd C*

    325 mg ferrous sulphate

    105 mg

    Ferro-tab

    200 mg ferrous fumarate

    65.7 mg

    Ferro-F-Tab

    310 ferrous fumarate

    100 mg

    Iron Melts

    25.4 mg ferrous fumarate

    5 mg

    Ferro-Liquid

    30 mg/mL ferrous sulphate

    6 mg/mL

    Maltofer tablets

    370 mg iron polymaltose

    100 mg

    Maltofer syrup or drops

    37 mg/mL iron polymaltose

    10 mg/mL

    * Modified release preparations

    Children requiring assessment

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

    Risk Assessment

    History and examination

    • Intentional overdose or accidental
    • Dose:
      • Stated or likely dose taken
      • Presented as syrup, immediate or enteric coated tablets
      • If possible determine the exact name and tablet size
      • Calculate the maximum possible dose per kg
    • Consider the possibility of Co-ingestants (e.g. paracetamol), either accidental or deliberate 

    Iron dose-response relationship (based on amount of elemental iron):

    • <20 mg/kg: asymptomatic
    • 20-40 mg/kg: GI symptoms only. Symptoms usually last <6hrs
    • 40-60 mg/kg: GI symptoms, systemic toxicity not expected. Symptoms usually last <8hrs
    • 60-120 mg/kg: potential for systemic toxicity
    • >120 mg/kg potentially lethal

    Symptoms and Signs:

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

    Phase

    Onset Post Ingestion/Duration

    Clinical features

    1: Gastrointestinal

    Due to direct injury from iron. May occur without systemic toxicity.

    0.5-6 hours

    Abdominal pain
    Vomiting
    Diarrhoea
    * Lack of symptoms within the first 6 hours makes significant toxicity unlikely.

    2: Quiescent/ latent

    6–24 hours

    Progressive increase in iron absorption & distribution
    Improvement of GI symptoms

    3: Cardiogenic shock and acidosis

    6–72 hours

    Hypotension
    Anion gap metabolic acidosis
    Potential multi-system failure
    Coma

    4: Hepatic necrosis

    12–96 hours

    Acute hepatic failure
    Jaundice
    Coagulopathy
    Hypoglycaemia
    Coma

    5: Bowel obstruction

    2–8 weeks

    Abdominal pain
    Vomiting
    Gastrointestinal fibrosis
    Cirrhotic liver disease

     Always check for a Medicalert bracelet in any unconscious patient, or any other signs of underlying medical condition (fingerprick marks etc.)

    Investigations

    Asymptomatic Children:

    • If tablet ingestion: Abdominal X-ray (AXR) - if negative, no further investigation or observation are required
    • If liquid ingestion: Abdominal X-rays are not indicated
    • If unknown amount or >40 mg/kg ingested: measure serum iron concentrations 4 hourly until falling or as per advice from toxicologist

    All symptomatic children should have the following investigations:

    • AXR: if tablet ingestion. It may also be helpful in evaluating gastrointestinal decontamination after whole bowel irrigation (WBI)
    • Blood gas: acidosis
    • Glucose: early hyperglycaemia, or hypoglycemia in the setting of acute hepatic dysfunction
    • Serum iron concentration
      • Immediately and repeat in 4 hours when iron concentration is expected to peak
      • Concentrations taken after 4-6 hours may underestimate toxicity because the iron may have either been distributed into tissues or be bound to ferritin
      • For 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
    • FBE: leukocytosis
    • UEC
    • LFTs
    • Clotting: reversible early coagulopathy and late coagulopathy secondary to hepatic injury
    • Blood group and cross-match

    Acute Management

    1. Resuscitation

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

    2. 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 60 mg/kg ingested
    • Discuss with a toxicologist (13 11 26) for advice before performing WBI
    • Usual protocol is nasogastric colonic lavage solution 30 mL/kg/hr until rectal effluent clear
    • 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:

    • 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
    • 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

    Desferrioxamine dose 

    • 15 mg/kg/hr intravenous
    • The rate is reduced after four hours so that the total intravenous dose does not exceed 80 mg/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 and on toxicologist advice
    • Desferrioxamine-iron complex is renally excreted. If oliguria or anuria develop, peritoneal dialysis or haemodialysis may become necessary to remove ferrioxamine

     Consider consultation/admission with local paediatric team when:

    • Ingestions of >40 mg/kg or unknown quantities
    • An intentional overdose.
    • Being considered for desferrioxamine or with worsening symptoms.

    Consult the Poisons Information Centre 13 11 26 for advice

    Consider transfer when:

    • Desferrioxamine and/or whole bowel irrigation is required
    • Significantly decreased or non-improving conscious state
    • Need for respiratory support
    • Children requiring care above the comfort level of the local hospital

    For emergency advice and paediatric or neonatal ICU transfers, call the Paediatric Infant Perinatal Emergency Retrieval (PIPER) Service: 1300 137 650.

    Consider discharge when:

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

    Assessing risk and connecting to community services

    • Prior to discharge, adolescents who present with deliberate ingestions need a risk assessment regarding the likelihood of further ingestions or other attempts to self-harm
    • Assessment of other drug and alcohol use should also be undertaken
    • If, after risk assessment, it is deemed safe to discharge a patient from hospital, but ongoing mental health or drug and alcohol needs are identified, the adolescent should be linked with appropriate services (see links below for services in the State of Victoria)

    Discharge information and follow-up:

    Parent Information Sheet: Poisoning prevention for children

    Victorian Poisons Information Centre: 13 11 26 www.austin.org.au/poisons

    Mental Health Services

    HEADSPACE:  National Youth Mental Health Foundation
    Local headspace centres:
    http://headspace.org.au/headspace-centres/

    CAMHS:  Child and Adolescent Mental Health Services
    Local services alphabetically by suburb / city:  
    http://www.health.vic.gov.au/mentalhealthservices/a.htm

    Drug and alcohol services

    YoDAA:  Victoria's Youth Drug and Alcohol Advice Service
    1800 458 685                           
    http://yodaa.org.au

    Last updated June 2020

  • Reference List

    1. National Poisons Centre New Zealand 2019, Iron- Oral Exposure, TOXINZ™ Poisons Information, viewed November 2019, <http://www.toxinz.com.acs.hcn.com.au/Search>
    2. Perth Children’s Hospital Emergency Department Guidelines 2019, Poisoning – Iron, viewed November 2019, <https://pch.health.wa.gov.au/For-health-professionals/Emergency-Department-Guidelines>
    3. IBM Micromedex 2019, Iron – Adverse Effects, viewed November 2019, <http://www.micromedexsolutions.com.acs.hcn.com.au/micromedex2/librarian?acc=36265>
    4. Liebelt, E. et al (UpToDate) 2019, Acute iron poisoning, viewed November 2019, <www.uptodate.com>