Sodium Deficit
Estimates sodium deficit in hyponatremia from weight and serum sodium.
When to use
Adults with hyponatremia to plan gradual correction and estimate the sodium amount needed.
Pearls and pitfalls
- The formula uses total body water and the difference between 140 mmol/L and current sodium.
- Correction should be gradual to reduce the risk of osmotic demyelination.
- The estimated deficit does not account for ongoing losses or the effect of administered fluids.
- Reassess sodium frequently and adjust the correction rate.
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Formula
Sodium deficit (mEq) = total body water (fraction × weight) × (140 − current sodium).
Evidence
Estimate used to plan hyponatremia correction, based on total body water and serum sodium.
References
- Adrogue HJ, Madias NE. Hyponatremia. N Engl J Med. 2000;342(21):1581-1589. doi:10.1056/NEJM200005253422107
Frequently asked questions
What is Sodium Deficit?
Estimates sodium deficit in hyponatremia from weight and serum sodium. Adults with hyponatremia to plan gradual correction and estimate the sodium amount needed.
How is the result calculated?
Sodium deficit (mEq) = total body water (fraction × weight) × (140 − current sodium).
How should the result be interpreted?
Estimate used to plan hyponatremia correction, based on total body water and serum sodium.
What are the sources?
Adrogue HJ, Madias NE. Hyponatremia. N Engl J Med. 2000;342(21):1581-1589.