Ethylene glycol and methanol poisoning vs Isopropyl alcohol poisoning
How to tell Ethylene glycol and methanol poisoning and Isopropyl alcohol poisoning apart when a board question makes them look alike.
Ethylene glycol = kidney/oxalate acidosis; methanol = eye/formate acidosis; isopropyl = ketosis without anion-gap acidosis.
Side by side
Ethylene glycol and methanol cause high anion-gap metabolic acidosis after toxic alcohol metabolism; ethylene glycol causes renal calcium oxalate crystals, while methanol causes visual injury.
Isopropyl alcohol causes ketosis without anion-gap metabolic acidosis, CNS depression, hemorrhagic gastritis, and acetone odor.
Alcohol dehydrogenase converts ethylene glycol to glycolic/oxalic acids and methanol to formic acid; fomepizole blocks this step.
Alcohol dehydrogenase converts isopropyl alcohol to acetone, producing ketosis and strong intoxication without organic acid accumulation; isopropyl alcohol is more intoxicating than ethanol by dose.
Osmolar gap early, anion-gap metabolic acidosis later, calcium oxalate crystals or hypocalcemia for ethylene glycol, and visual symptoms for methanol support toxic alcohols treated with fomepizole.
Ketosis with normal anion gap, elevated osmolar gap, acetone, CNS depression, and gastritis support isopropyl alcohol poisoning.
The trap
All can raise the osmolar gap early, so the anion gap, target organ, and ketone pattern decide.
The repair move
For toxic alcohols, map the metabolite to the organ injury and acid-base pattern.
Try a free question
CoreA patient drinks antifreeze and develops flank pain, hypocalcemia, anion-gap metabolic acidosis, and envelope-shaped calcium oxalate crystals in urine. Which poisoning is most likely?
Show answer and explanation
Answer: A. Ethylene glycol poisoning. Antifreeze exposure with renal injury, hypocalcemia, calcium oxalate crystals, and anion-gap metabolic acidosis supports ethylene glycol poisoning.
Why the other choices are tempting
- B. Methanol causes visual injury and formic-acid acidosis.
- C. Isopropyl alcohol causes ketosis without an anion-gap metabolic acidosis.
- D. Ethanol intoxication does not produce calcium oxalate crystals.
- E. Cyanide poisoning causes cellular hypoxia and lactic acidosis.
Flashcards
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What finding points to ethylene glycol poisoning?
Calcium oxalate crystals, renal injury, hypocalcemia, and anion-gap metabolic acidosis point to ethylene glycol.
What finding points to methanol poisoning?
Visual symptoms with anion-gap metabolic acidosis point to methanol poisoning.
Quick answers
What is the fastest way to tell Ethylene glycol and methanol poisoning from Isopropyl alcohol poisoning?
Ethylene glycol = kidney/oxalate acidosis; methanol = eye/formate acidosis; isopropyl = ketosis without anion-gap acidosis.
What is the key clue for Ethylene glycol and methanol poisoning?
Ethylene glycol and methanol cause high anion-gap metabolic acidosis after toxic alcohol metabolism; ethylene glycol causes renal calcium oxalate crystals, while methanol causes visual injury.
What is the key clue for Isopropyl alcohol poisoning?
Isopropyl alcohol causes ketosis without anion-gap metabolic acidosis, CNS depression, hemorrhagic gastritis, and acetone odor.
What is the common trap with Ethylene glycol and methanol poisoning vs Isopropyl alcohol poisoning?
All can raise the osmolar gap early, so the anion gap, target organ, and ketone pattern decide.