Iron - Dr. Beuhler

Iron

    - Metals in salt form cause VOMITING
    - 2+ ferrous sulfate in absorbable state → 3+ state for storage/transfer

Chewable tablets
    - 10-18mg/tab
    - Hard to overdose on these - “minimally toxic”

Iron carbonyl
    - elemental iron
    - low toxicity

Iron filings in hand warmers → if ingested, could be toxic

Prenatal vitamins
    - greatest morbidity
    - look like candy

• When considering overdose, must calculate the dose of elemental Fe ingested
• Varies based on the substance, so just look up -- or Call Poison Control!
• Toxic dose starts at 20-60mg/kg
• >60mg/kg -- concern 
• If no vomiting associated, probably ok and not at toxic level
  

Injuries

• GI -- mucosal damage, ulceration, perforation, hemorrhage, strictures
• CV -- decreased cardiac contractility, vessel injury, 3rd spacing of fluid
• Liver -- a hepatotoxin -- periportal necrosis, sequestered in 1st pass metab, coagulopathy, hyperammonemia, hypoglycemia
  

5 stages of toxicity

1. ingestion to 6h

    - vomiting!!
    - abd pain
    - diarrhea
    - melena/hematemesis
    - bowel wall necrosis/infarct

2. 6h - 24h

    - quiescent stage
    - symptoms appear to resolve
    - continued worsening acidosis
    - if ingestion was small → course usually stops here
    - if ingestion was large → this stage is sometimes skipped and go onto more badness

3. 12h - 48h

    - crash
    - CV, Liver, GI, ARDS, CNS lethergy/coma, Acidosis

4. 2d - 3d

    - independent of severity of stage 3
    - fulminant hepatic failure
    - >1000 iron level

5. weeks later

    - mucosal injuries/strictures

Iron Levels

• Iron levels peak around 2-6 hr, longer if enteric coated tablets
• Level not a reliable indicator of toxicity
• 300-500 -- systemic toxicity
• >500 → treat
• Get a level before started deferoxamine
  

Workup

   - electrolytes -- AGMA
   - coags if bleeding
   - LFTs if sick
   - APAP level for intentional ingestion -- think about synergy

   - x-rays -- abd → see pills sometimes

Management

• obs for 6 h if asxs → ok → home
• no GI or acidosis
  

• if sxs, esp GI or acidosis → admit for obs
• get iron level
• fluid resuscitation
• no lavage/charcoal/ipecac/bicarb
• may consider whole bowel irrigation if positive xray

• Deferoxamine
• specific antedote for iron
• no heme/cytochrome iron binding
  

        use:

            hx of sxs, pos xrays, super high iron level
            100mg binds 10mg iron

        IV admin -- 15mg/kg/hr for rate but may not get in enough

        Side Effects:

            hypotension, tachycardia, diuresis

            visual/ototoxicity, abd pain, fever, diarrhea

            increased risk for yersenia enterocolitica sepsis

        stop when acidosis resolves

Core Concepts:

    elemental dose is what’s toxic

    no charcoal for tx

    look for anion gap metabolic acidosis

    check an xray for pills, but if it’s negative doesn’t mean pt isn’t sick

    there’s a quiescent phase of toxicity

    deferoxamine is an option for iron chelation

    pay attention to units used to quantify iron --usually in dL

       

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