Osmolar Gap Toxic Alcohol — ESENeph MCQ

Correct answer: D — Methanol poisoning causing both an osmolar gap and formate-mediated acidosis

The best answer is “Methanol poisoning causing both an osmolar gap and formate-mediated acidosis”. The osmolar gap is approximately 30 mOsm/kg. Methanol is metabolized to formate, producing high-anion-gap acidosis and visual toxicity; fomepizole and urgent toxicology and dialysis assessment are required. “Uraemic acidosis with advanced kidney failure and a normal osmolar gap” is less appropriate because the marked osmolar gap and visual symptoms point to a toxic alcohol “Diabetic ketoacidosis with marked hyperglycaemia and a normal osmolar gap” is less appropriate because the metabolic and osmolar pattern lacks hyperglycaemic ketoacidosis evidence “D-lactic acidosis causing a high osmolar gap” is less appropriate because D-lactate does not create this toxic-alcohol osmolar pattern “Salicylate poisoning causing isolated metabolic alkalosis” is less appropriate because salicylate typically creates a mixed respiratory alkalosis and metabolic acidosis without this visual-toxic-alcohol pattern

Reference: EXTRIP recommendations for methanol poisoning: https://www.extrip-workgroup.org/methanol