Paediatricsmiddle twist
A 4-year-old girl is admitted with four days of diarrhoea. She is 10 per cent dehydrated but not shocked, and her serum sodium on arrival is 172 mmol/L (135-145). Intravenous rehydration is commenced. Eight hours later the sodium is 148 mmol/L, she has become progressively drowsy, and she then has a generalised tonic-clonic seizure lasting three minutes. Her blood glucose is 5.8 mmol/L, ionised calcium is normal and she is afebrile. Which one of the following best explains her deterioration?