A 4-month-old boy was admitted with diarrhoea, poor oral intake, vomiting, lethargy and convulsions. Serum electrolyte levels were: sodium 199 mEq/l, potassium 6.3 mEq/l, calcium 7.6 mg/dl, phosphorus 5.2 mg/dl, BUN 47 mg/dl and creatinine 1.1 mg/dl. Brain CT showed bilateral symmetrical hypodensities in the thalami (Fig. 1). He was treated for hypernatraemic dehydration with appropriate IV fluid and electrolyte therapy. His condition deteriorated and he died following cardiac arrest 10 h later.