Ethylene glycol toxicity

Summary

• AGMA with osmolar gap, hypocalcemia, AKI, hematuria, and obstruction
• Osmolar gap becomes anion gap as metabolism progresses

Pathophysiology

graph TD
eg["Ethylene glycol"] --> |Alcohol dehydrogenase|glycerald
glycerald["Glyceraldehyde"] --> |Aldehyde dehydrogenase|glycolate
glycolate["Glycolate"] --> glycox
glycox["Glycoxylate"] --> |Thiamine & pyridoxine|metabs["Less toxic metabolites"]
glycox --> oxalate
oxalate["Oxalate"] --> |Calcium|caox
caox["Calcium oxalate"]

• Glycolate causes renal tubular damage and oxalate crystal cause urinary obstruction
• Hypocalcemia secondary to calcium oxalate formation

Sources

• Antifreeze
• Windshield fluid
• Cleaners
• Fuels
• Moonshine

Clinical Manifestations

• Decreased LOC
• Hematuria with flank pain and oliguria
• Hypocalcemia
  • Cranial nerve palsies
• Coma, seizures, tachypnea, and hypotension in late stage

Investigations

• Anion gap metabolic acidosis with osmolar gap
  • As metabolism progresses the initial osmolar gap is replaced by an anion gap
• Order acetaminophen and salicylate levels as well
• Lactate can be elevated, either because of lactate or because of false-positive from the ethylene glycol
• Monitor renal function, including electrolytes, extended lytes (calcium), and creatinine
• Urine microscopy for calcium oxalate crystals, which show up as needle-shaped crystals
• Monitor ECG for QTc prolongation from hypocalcemia

Management

• ABCs
• NG aspiration if within 60 minutes
• Sodium bicarb if pH <7.3, with infusion to target pH ≥ 7.35
• Thiamine and pyridoxine to shunt glycoxylate metabolism toward less harmful metabolites
• Fomepizole or ethanol, which competitively inhibit alcohol dehydrogenase
  • Serum ethylene glycol >3.2 mmol/L, or
  • Documented toxic ingestion and an osmolar gap > 10, or
  • Suspected toxic ingestion and 2 of:
    • pH < 7.3
    • Bicarb < 20
    • Gap (which one?) > 10
    • Urinary oxalate crystals
• Hemodialysis if ongoing acidosis and evidence of end-organ damage