-Unreplaced water loss (which requires an impairment in either thirst or access to water):
- Insensible and sweat losses;
- GI losses;
- Central or nephrogenic diabetes insipidus;
- Osmotic diuresis;
- Glucose in uncontrolled DM;
- Urea in high-protein tube feedings;
- Mannitol
–Hypothalamic lesions impairing thirst or osmoreceptor function
–Water loss into cells e.g. with severe exercise or seizures
–Sodium overload (iatrogenic) e.g. Intake or administration of hypertonic sodium solutions