🧪 Sodium Deficit (Hyponatraemia)
Estimate the sodium deficit to plan correction in hyponatraemia.
Clinical takeaway
Estimates total mmol, not the infusion rate.
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When to use
Quantify sodium needed to reach a target in hyponatraemia.
How it works
Na deficit = TBW × (target Na − current Na), TBW = factor × weight (0.6 male, 0.5 female/elderly).
Key points
- Estimates total mmol, not the infusion rate.
- Limit correction to ≤ 8–10 mmol/L per 24 h (less if high risk).
- Over-rapid correction risks osmotic demyelination.
References
Decision support for licensed clinicians only; not a substitute for clinical judgement, diagnosis or local protocols.
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| Weight | 70 kg |
|---|---|
| Current sodium | 120 mmol/L |
| Target sodium | 130 mmol/L |
| Total body water factor | Adult male (0.6) |
→Sodium deficit420mmol
- Total body water：42.0 L
- Formula：TBW × (target Na − current Na)
- Correction limit：Raise Na by ≤ 8–10 mmol/L per 24 h (≤ 4–6 if very high risk) to avoid osmotic demyelination.
| Weight | 70 kg |
|---|---|
| Current sodium | 120 mmol/L |
| Target sodium | 130 mmol/L |
| Total body water factor | Elderly female (0.45) |
→Sodium deficit315mmol
- Total body water：31.5 L
- Formula：TBW × (target Na − current Na)
- Correction limit：Raise Na by ≤ 8–10 mmol/L per 24 h (≤ 4–6 if very high risk) to avoid osmotic demyelination.
Frequently asked questions
- What is Sodium Deficit (Hyponatraemia)?
- Estimate the sodium deficit to plan correction in hyponatraemia.
- How is Sodium Deficit (Hyponatraemia) calculated? What is the core formula?
- Na deficit = TBW × (target Na − current Na), TBW = factor × weight (0.6 male, 0.5 female/elderly).
- When is Sodium Deficit (Hyponatraemia) used?
- Quantify sodium needed to reach a target in hyponatraemia.
- What are the key clinical points for Sodium Deficit (Hyponatraemia)?
- Estimates total mmol, not the infusion rate. Limit correction to ≤ 8–10 mmol/L per 24 h (less if high risk). Over-rapid correction risks osmotic demyelination.
- What are the limits and cautions when using Sodium Deficit (Hyponatraemia)?
- For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
- How is Sodium Deficit (Hyponatraemia) calculated in practice? Can you show a worked example?
- Inputs: Weight 70 kg, Current sodium 120 mmol/L, Target sodium 130 mmol/L, Total body water factor Adult male (0.6) → Result: Sodium deficit 420 mmol（Total body water: 42.0 L, Formula: TBW × (target Na − current Na), Correction limit: Raise Na by ≤ 8–10 mmol/L per 24 h (≤ 4–6 if very high risk) to avoid osmotic demyelination.） Inputs: Weight 70 kg, Current sodium 120 mmol/L, Target sodium 130 mmol/L, Total body water factor Elderly female (0.45) → Result: Sodium deficit 315 mmol（Total body water: 31.5 L, Formula: TBW × (target Na − current Na), Correction limit: Raise Na by ≤ 8–10 mmol/L per 24 h (≤ 4–6 if very high risk) to avoid osmotic demyelination.）