Iron Poisoning ✅ Flashcards
Why is iron poisoning a significant cause of toxicological mortality in young children?
Due to its presence in the environment as a result of supplementation for pregnant and breastfeeding mothers
What is broadly related to the severity of iron toxicity?
The amount of elemental iron ingested
Generally, ingestion of what amount of elemental iron will cause toxic effects?
10-20mg/kg
Generally, ingestion of what amount of elemental iron can lea to severe effects and potential death?
50-60mg/kg
What causes toxicity in iron overdose?
Total iron binding capacity is saturated, and free ferric iron (Fe3+) is present. This leads to production of hydroxyl free radicals, causing lipid peroxidation, which results in local tissue injury
What are the primary sites of local tissue injury in iron overdose?
The gut and liver
What are the initial symptoms of iron toxicity?
- Nausea and vomiting, with possible haematemesis
- Diarrhoea
- Abdominal pain
What might happen following the initial symptoms of iron toxicity?
They may be an improvement in symptoms
What is the problem with the initial improvement in symptoms after the initial phase of iron toxicity?
Can mask evolving raised anion gap metabolic acidosis
What causes the raised anion gap metabolic acidosis in iron toxicity?
Disturbance of mitochondrial function
What can occur following the metabolic acidosis in iron toxicity?
Multi-organ failure
What is the often the first organ to be affected in iron toxicity?
Liver
Why is the liver often the first organ to be affected in iron toxicity?
As a result of early exposure during first pass metabolism
How might the GI system be affected in iron poisoning?
In survivors of severe iron poisoning, intestinal mucosal injury may lead to the formation of strictures
Where is the most common location for strictures caused by iron poisoning?
Pylorus of the stomach
What investigation may be useful in predicting toxicity in asymptomatic iron poisoning patients?
Serum iron concentrations 4 hours after ingestion
At what serum iron concentration 4 hours after ingestion would significant toxicity be very unlikely?
Under 60µmol/L (following administration of immediate release preparations)
Why might measurement of serum concentrations of iron after 4 hours underestimate toxicity?
Due to redistribution of iron to tissues and binding to ferritin
When might serial serum iron concentrations be useful?
- Monitoring asymptomatic patients
- Monitoring those who have ingested slow release or enteric coated formulations
Is activated charcoal useful in iron poisoning?
No
Why is activated charcoal not useful in iron poisoning?
It is not absorbed by activated charcoal
What are the treatment options for iron poisoning?
- Whole bowel irrigation
- Desferrioxamine
How does whole bowel irrigation help in iron poisoning?
It may be effective in reducing absorption
When is whole bowel irrigation recommended in iron poisoning?
Ingestions of >60mg/kg of elemental iron
What is desferrioxamine?
A bacterially-derived iron chelating agent
How does desferrioxamine help in iron poisoning?
It binds free iron and enhances its elimination in urine
When is desferrioxamine indicated in iron poisoning?
All cases with signs of systemic intoxication, especially those with raised anion gap metabolic acidosis
Should you wait for serum iron concentration results before starting treatment with desferrioxamine in patients with symptomatic iron poisoning?
No
How long should desferrioxamine treatment be continued for in iron poisoning?
Until acidosis is reversed and patient is asymptomatic
Why do you need to continue until the patient is asymptomatic when treating iron poisoning with desoferrioxamine?
Desferrioxamine interferes with most laboratory assays for serum iron and therefore this measure cannot be used to monitor response to therapy
