see also: [paediatric Fe overdose VBG case](x-devonthink-item://645DC5F2-F669-4F46-AF3E-9E5F4A066001?page=84) > [!pearl] Key Points > - **risk_dose**:: >60mg/kg, 90 micromol/L (serum) > - **Antidote**:: desferrioxamine, [[Decontamination#Whole bowl irrigation]] > - **key_points**:: > - Iron has two distinct toxic effects: (1) direct caustic injury to the gastrointestinal mucosa, and (2) impaired cellular metabolism, primarily of the heart, liver, and central nervous system > - all systemic toxicity has GI symptoms > - HAGMA metabolic acidosis, coagulopathy, initial hyperglycaemia > - classically describe 5 phases > - metabolic acidosis is itself an indication for desferrioxamine > > **desferrioxamine** 15mg/kg/h is indicated if if systemic toxicity (shock, metabolic acidosis, altered mental status) or serum iron level is *>90 micromol/L* (500mcg/dL) at 4-6 h post ingestion Iron supplements are readily accessible to pregnant women and thus are frequently taken in overdose. The *fetus is relatively protected* unless maternal cardiovascular instability develops. Therapy is directed towards *care of the mother* and does not differ from the care of the non-pregnant patient. - used to be leading cause of poisoning death in children; *labelling* the packaging lead to an abrupt decrease in number of poisonings and deaths # Risk assessment > In an iron overdose, determining the amount of elemental iron ingested is most important, because cellular toxicity depends on the effects of elemental iron. Different formulations of iron salts contain different percentages of elemental iron amount of elemental iron in a ferrous or ferric salt is calculated: - Ferric chloride dose divided by 3.5 - Ferrous chloride dose divided by 4 - Ferrous fumarate dose divided by 3 - Ferrous gluconate dose divided by 9 - Ferrous sulfate (dried) dose divided by 3.3 - Ferrous sulfate (heptahydrate) dose divided by 5 | Iron dose (mg/kg) | effect | | ---- | ---- | | < 20 | asymptomatic | | 20-60 | GI symptoms | | 60-120 | systemic toxicity | | >120 | potentially lethal | # Toxic Mechanism - direct corrosive effect on GI mucosa → vomiting, diarrhoea, haematemesis, melena. - large GI fluid losses → significant hypovolaemia - *systemic toxicity does not occur in the absence of GI symptoms* - Fe acts as a direct cellular toxin (unclear mechanism), mostly on cardiovascular system and liver - Severe **metabolic acidosis** with high [[Lactic acidosis|lactate]] following large overdoses - **coagulopathy** observed - hepatorenal failure # Clinical features Stages | Time post | clinical features | | --------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------ | | 0-6 h<br>*Gastrointestinal* | direct corrosive effect on **GI tract**; vomiting, diarrhoea, abdo pain, fluid losses/ shock | | 6-12 h<br>*latent* | increased Fe absorption and re-distribution, some resolution of symptoms giving false hope of recovery. cellular toxicity continues. | | 12-48 h<br>*systemic* | disruption of cellular metabolism. vasoplegic **shock** + 3rd space losses, [[Blood gas#anion gap]] metabolic acidosis, **hepatorenal failure** | | 2-5 d<br>*hepatic* | acute **liver failure**, jaundice, coma, [[hypoglycaemia\|hypoglycemia]], coagulopathy. rare, but high mortality | | 2-6 weeks<br>*obstructive* | delayed sequelae, cirrhotic liver disease, GI fibrosis/strictures | # Treatment **Desferrioxamine** - indicated if systemic toxicity (shock, metabolic acidosis, altered mental status) or *serum iron level is >90 micromol/L* (500mcg/dL) at 4-6 h post ingestion - Where serum iron levels are not readily available, ==a fall in serum bicarbonate concentration is a good surrogate marker of systemic iron poisoning== and, in conjunction with worsening clinical features, would justify desferrioxamine administration. - need cardiac monitoring during administration - *adverse reactions:* hypersensitivity, hypotension (reduce rate if this occurs), possible ARDS, retinopathy, yersinia sepsis and mucoormycosis (ferrioxamine complex acts as a siderophore promoting grown of these organisms) - *dose:* ==15mg/kg/h==. increase rate up to 40mg/kg/h in life-treatening tox - *end point:* patient stable, iron <60 micromol/L (350 microgram/dL) - [[Decontamination#Whole bowl irrigation]] for significant iron tablet ingestions (not useful if liquid or chewable iron) - may reduce need for chelation therapy - use **polyethylene glycol-electrolyte** solution (PEG-ELS) via NGT - 500mL/h age 9 months-6 years - 1000mL/h children 6-12 - 1.5-2L/H in adolescents and adults - WBI continues until rectal effluent is clear nad no radiographic evidence of pill fragments - contraindicated if bowel obstruction, perforation, ileus, or haemodynamic instability - Surgical or endoscopic removal of tablets if lethal ingestion (e.g. >120mg/kg) or WBI not feasible - If renal failure would need haemodialysis, but this is not a dialisable toxidrome # Disposition - *Children* with <40mg/kg may be managed at home if asymptomatic - child asymptomatic at *6 hours* and has negative abdo XR for iron can be discharged - If *adult* had <60mg/kg and asymptomatic at 6 hours, can be discharged - symptomatic pts requiring IVF or WHI need admission ; anyone with established systemic iron toxicity or requiring IV chelation need ICU # Related Questions ## iron ingestion - [x] 2Q: [Iron Ingestion](x-devonthink-item://40F10AFA-5F29-4EE4-B149-300627B498B0?page=16) -- [Answer](x-devonthink-item://2088AEED-9FCF-4CF0-B58D-E4279D4BCC76?page=38) ## iron toxicity - [ ] 2Q: [Iron toxicity](x-devonthink-item://4BE7EDE1-1843-4BA0-B8D2-0DCEF50784D4?page=3) -- [Answer](x-devonthink-item://15F8F701-8EC8-4F9A-8DEC-5220C8561C8A?page=3) -- [prop](x-devonthink-item://281EC7A9-8E5A-461A-AA34-3FF490AA0EC2?page=4) - [ ] 3Q: [Iron toxicity](x-devonthink-item://85167CB5-A7B5-4BF3-9BC7-AC46D5538A42?page=4) -- [Answer](x-devonthink-item://5B03E66C-E043-4EB7-A5F6-7389CB927BD7?page=6)