- Why are they on IV fluids? Eating or drinking at all?
- Weight? Latest U&E?
- Any heart failure, AKI, or ongoing losses (vomiting, drains, NG)?
Do now
- Decide the purpose: resuscitation, maintenance, or replacement
- Assess volume status and check U&E
- Use weight to calculate maintenance
- Add ongoing losses separately
- Review daily — stop when they can drink
Key doses
- Maintenance (NICE CG174): water 25–30 mL/kg/day; Na⁺, K⁺, Cl⁻ ~1 mmol/kg/day each; glucose 50–100 g/day
- Resuscitation: 500 mL crystalloid over < 15 min, reassess
- Frail, elderly, heart failure or renal impairment: consider 20–25 mL/kg/day
Typical adult doses — always check the BNF and your local guideline.
Call your senior if
- Abnormal sodium or potassium
- Heart failure or overloaded
- Large ongoing losses
Think of
- Hyponatraemia from hypotonic fluids
- Overload in the frail
- Hypokalaemia if no potassium added
Go deeper
The full walkthroughs behind this call.