LAUSR

The differential diagnosis of hyponatraemia is notoriously wide. However, only a minority is acute, ie develops in less than 48 hours. We describe an unusual cause of water intoxication due to toothache. A 30-year-old man with no medical history of note presented in an acute confusional state. Laboratory results disclosed profound hyponatraemia. Urinary indices were consistent with overdrinking, but in the absence of a reliable history, other aetiologies had to be excluded. This case highlights the benefit of a structured approach in the assessment of electrolyte disturbances.