Major criteria Minor criteria
Plasma osmolarity < 280 mOsm/L Inappropriate urine osmolarity > 150 mOsm/L Normal extracellular volume: no orthostatic hypotension, tachycardia, oedema or ascites Natriuresis > 30 mmol/L on a normosed diet Normal thyroid and adrenal function No recent use of diuretics No correction of the natremia after infusion of 0.9% saline Correction of the natremia after water restriction