Sodium Deficit Calculator

Your details

Sets the total body water fraction of body weight.
kg
Measured serum sodium from a recent blood test.
mEq/L
Desired serum sodium. 140 mEq/L is the usual default.
mEq/L
A common cautious target is about 0.5 mEq/L per hour, capped at the 24 hour ceiling.
mEq/L per hour
Daily ceiling to limit osmotic demyelination risk. 8 mEq/L is common; 6 in high-risk patients.
mEq/L
Sodium deficitLarge gap, correct slowly
630mEq
Total body water42L
Sodium gap (target - current)15mEq/L
Time to correct (at safe rate)45h
Sodium for the first 24 h336mEq
Max rise in 24 h ceiling8mEq/L
Current sodium125mEq/L
Target sodium140mEq/L
125 mEq/L
Severe<125Moderate125-130Mild130-135Normal135+

Estimated sodium deficit is about 630 mEq to reach the target.

  • This is the total sodium gap, not an infusion rate; the rate and fluid choice are set by the treating clinician.
  • Limit the rise to about 8 mEq/L in any 24 hour period (lower in high-risk patients) to reduce osmotic demyelination risk.
  • At 0.5 mEq/L per hour the gap would take about 45 hours to close, spread over more than one day if the daily ceiling applies.

Next stepUse the deficit with a clinician-chosen sodium concentration to plan the correction over the appropriate time, re-measuring sodium frequently.

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