Podcasts · Core EM - Emergency Medicine Podcast

Episode 229: Iron Poisoning

· 12 min · Episode 229

Episode Episode 229: Iron Poisoning

0:00 12:20

Iron overdose in the ED: five stages, elemental iron math, decontamination, and deferoxamine.

Hosts: Brian Chastain, MD Brian Gilberti, MD

https://media.blubrry.com/coreem/content.blubrry.com/coreem/Iron_Poisoning.mp3

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Show Notes Core EM Modular CME Course

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Click Here to Register and Begin Module 1 Iron Poisoning Stages at a Glance

Stage Timing What’s happening 1 · GI 30 min–6 h Direct corrosive GI injury; abd pain, vomiting 2 · Latent 6–24 h GI sx improve; iron redistributing into tissues 3 · Shock / acidosis 6–72 h Profound metabolic acidosis → shock, MSOF 4 · Hepatotoxicity 12–96 h Hepatotoxicity → fulminant liver failure 5 · GI scarring 2–8 wks Gastric outlet obstruction, GI tract scarring

The Case

• 31M w/ hx depression, anxiety; found minimally responsive at home by family • EMS: HR 67, SpO2 96% on 2 L NC, BP 46/21; withdraws to pain, not opening eyes → 2 L IVF + push-dose epi en route • ED: BP ↑ to 90/61, other VS unchanged; dried vomit on lips/shirt; breathing comfortably, protecting airway • POC VBG: pH 7.24, pCO2 33, pO2 25, HCO3 14, lactate 2.5 • ECG: NSR, otherwise unremarkable → get an ECG in any possible toxic ingestion • Additional 30 mL/kg bolus + norepi gtt • Family arrives → bottle of iron pills under the pt’s bed

Pathophysiology

• Free iron = multisystem oxidative injury • Primary mechanism: free radical generation + lipid peroxidation → damages cellular and mitochondrial membranes throughout the body • Profound metabolic acidosis via 2 routes: uncoupled oxidative phosphorylation → anaerobic metabolism → lactate; Fe³⁺ reacts w/ water → releases 3 H⁺ → excess acid • Direct mucosal necrosis in the gut (corrosive injury) • Negative inotrope on the myocardium → hypotension, cardiogenic shock in large ingestions

Clinical Stages

• Classic progression after large ingestions; stages overlap and pts can present anywhere along the timeline • Stage 1, GI (30 min–6 h): direct GI tract injury; abd pain, vomiting. Persistent vomiting = very sensitive indicator of a serious ingestion • Stage 2, latent (6–24 h): GI sx improve, but iron is redistributing into the tissues → ongoing damage • The latent-phase trap: pts look like they’re turning the corner right before they crump. Contrast: pts never symptomatic >6 h after ingestion are unlikely to develop toxicity (AAPCC 2005); GI sx that improve ≠ never symptomatic • Stage 3, shock (6–72 h): tissue iron → profound acidosis → shock, MSOF • Stage 4, hepatotoxicity (12–96 h): hepatotoxicity → fulminant liver failure • Stage 5, GI scarring (2–8 wks): gastric outlet obstruction, GI tract scarring from the initial corrosive injury

Diagnosis / Workup Imaging

• Emergent plain-film abd XR in any suspected iron ingestion → intact adult iron tabs are radiopaque • Confirms pills still in the stomach/GI tract → helps decide on WBI • Negative XR ≠ no ingestion: chewables, liquid formulations and already-dissolved tabs often don’t show up

Serum Iron

• Draw 4–6 h post-ingestion for regular formulations, ~8 h for extended release • Often hard to interpret → time of ingestion and formulation frequently unknown • >500 mcg/dL → serious systemic toxicity • >1,000 mcg/dL → very significant mortality

Elemental Iron Math

• Toxicity tracks the elemental iron dose, not the mass of the pill

Salt Elemental Fe Per 325 mg tab Ferrous sulfate ~20% ~65 mg Ferrous fumarate ~33% 106 mg Ferrous gluconate ~12% ~36–38 mg

• <20 mg/kg elemental Fe → usually…

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