Calcium oxalate nephrolithiasis is commonly associated with ingestion of which toxin?

• A. Ethylene glycol
• B. Methanol
• C. Isopropyl alcohol
• D. Ethanol

Answer: (D)

Calcium oxalate stones form when oxalate combines with calcium in the urine. A classic toxin that raises oxalate levels and leads to stone formation is ethylene glycol (found in antifreeze). After ingestion, it’s metabolized by alcohol dehydrogenase into glycolic and oxalic acids. Oxalic acid binds calcium to create calcium oxalate crystals, which can precipitate in the kidneys and urine, causing nephrolithiasis and potential kidney injury.

Other alcohols listed don’t produce oxalate in amounts that cause these stones; methanol mainly leads to formic acid accumulation and metabolic acidosis, while isopropyl alcohol and ethanol aren’t associated with calcium oxalate stone formation.