Iron Flashcards
MCQ:
What paediatric dose can be managed at home provided they are asymptomatic?
<40mg/kg
How to calculate quantities of different elemental irons
Divide all oral preparations by 3
Gluconate divide by 9
ferrous sulfate divide by 5
What doses mg/kg cause what symptoms?
<20mg/kg = asymptomaitc
<40mg/kg = GI
>60-120mg/kg = systemic
>120mg/kg = life threatening
How does iron absorption occur?
Ferrous (Fe2+) is normally oxidised in enterocytes into Ferric (Fe3+) -> in overdose this is overwhelmed so massive increase in free serum iron (Fe2+)
What are the 5 clinical stages of iron toxicity
In reality it doesn’t happen in 5 stages and there’s huge overlap but you need to know it like this for the SAQ
0-6hrs: Direct corrosive GI effect with large GI fluid loss
6-12hrs: GI Sx improve and “apparent” resolution of toxicity
12-48hrs: Mitochondrial toxicity = metabolic acidosis + vasodilatory shock + M.O.F
2-5 days: hepatic failure, coma, hypoglycaemia, coagulopathy
2-6 weeks: GI tract fibrosis and strictures
Investigations
Abdominal x-ray:
significant iron deposition may warrant whole bowel irrigation
Iron level:
Peak 4-6 hrs
>90mmol/L correlates with systemic toxicity
What treatments and what thresholds for using them?
Whole bowel irrigation
>60mg/kg OD + visible deposition on AXR
Desferroxamine: 15mg/kg/hr
Indicated in shock/metabolic acidosis/altered mentation
OR
>60mg/kg Fe with visible AXR deposition
WBI Performed by putting 1-2L and hour of polyethylene glycol electrolyte solution through bowel via an NGT and run it until rectal effluence is clear
Use metoclopramide to reduce vomiting + increase bowel transit
Side effects of desferroxamine:
HYpotension (slow infusion)
ARDS (prolonged infusions >24hr)
Toxic retinopathy
ferrioxamine complex acts as a siderophore (iron donating) which can promote yersinia growth causing secondary bacterial infection
