Characterised by:

• hyponatraemia secondary to the dilutional effects of water retention
• Concentrated urine
• Euvolaemic state

Causes

• ecstasy poisoning

PC

• Dehydration (caused by low Na)
• nausea
• headache
• vomitting
• tremors
• muscle cramps

Very low serum Na levels can lead to cerebral oedema - mood swings, confusion, hallucinations

Investigations

• Urea and electrolytes: shows a hyponatraemia