A two-year-old boy presents with fever for 3 days which responded to administration of paracetamol. Three days later he developed acute renal failure, marked acidosis and encephalopathy. His urine showed plenty of oxalate crystals. The blood anion gap and osmolar gap were increased. Which of the following is the most likely diagnosis –

ETHYLENE GLYCOL POISONING Ethylene glycol is metabolized by Alcohol dehydrogenate in the liver to Glycoaldehyde → Glyoxalic acid → Oxalic acid Toxicity is caused by oxalic acid Toxicity occurs in 3 stages Early symptoms (1-12 hr) - Gastric irritation, nausea, Vomiting, drowsiness, metabolic acidosis begins to develop. Symptoms at 12-24 hours - Cardiac dysrhythmia, muscle pain, tetany due to hypocalcaemia which occur due to binding and calcium with oxalic acid. Later stage (After 24 hrs) - Cardiac failure, seizure, cerebral edema and renal failure. Renal failure is caused due to deposition of calcium oxalate crystal in renal tubules. Calcium oxalate crystals are commonly seen in urine on microscopy. Management - Intravenous sodium bicarbonate at doses of 1-2 mEq/Kg. Ethanol and/or Fomepizole to inhibit the metabolism of ethylene glycol. Hemodialysis effectively removes ethylene glycol.