Back to Basics: Methanol and Ethylene Glycol Toxicity
Background
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Methanol found in paint products, windshield wiper fluid, and antifreeze
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Ethylene glycol found in antifreeze, brake fluid, and some detergents
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Methanol and ethylene glycol are metabolized in the liver to toxic compounds by alcohol dehydrogenase
Clinical
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Methanol Poisoning = symptoms often occur 12 to 24 hrs after ingestion, altered mental status / visual problems / abdominal pain / nausea / vomiting, gastritis / pancreatitis, papilledema
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Ethylene Glycol Poisoning = initial 12 hrs present as intoxication (nausea / vomit / slurred speech / ataxia / altered mental status), 12 to 24 hrs after ingestion predominately cardiopulmonary effects (tachycardia, tachypnea, hypertension, CHF, ARDS), 24+ hrs after ingestion predominately renal effects (flank pain, hematuria, oliguria / anuria, ATN, ARF)
Diagnosis
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Metabolic acidosis with elevated anion gap and elevated osmolal gap
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Serum methanol and ethylene glycol levels available at most labs
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Calcium oxalate crystals in urine with ethylene glycol
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VBG / ABG useful to assess severity of acidosis
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ECG : ethylene glycol can cause hypocalcemia (prolonged QT interval)
Treatment
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Supportive care
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Fomepizole and ethanol both have greater affinity for alcohol dehydrogenase and can block metabolism to toxic compounds
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Methanol, ethylene glycol, and their toxic metabolites are all dialyzable
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Other: methanol - folate, ethylene glycol - pyridoxine and thiamine
REFERENCES
Tintinalli, JE. Tintinalli's Emergency Medicine: A Comprehensive Study Guide. 8th ed. New York, NY: McGraw-Hill Education LLC, 2016.