Sodium Deficit Calculator
Calculate the amount of sodium needed to correct hyponatremia safely
Calculate Sodium Deficit
Patient's current body weight
Used for total body water calculation
Affects total body water percentage calculation
Normal range: 136-145 mEq/L (equivalent to mmol/L)
Default: 140 mEq/L (normal physiological level)
Example Calculation
Adult Female Patient Example
Weight: 55 kg
Age: 45 years (adult)
Sex: Female
Current Serum Sodium: 125 mEq/L
Target Sodium: 140 mEq/L
Step-by-Step Calculation
1. TBW = 55 kg × 0.50 (adult female) = 27.5 L
2. Sodium deficit = 27.5 L × (140 - 125) mEq/L
3. Sodium deficit = 27.5 × 15 = 412.5 mmol
Result: 412.5 mmol sodium needed
Safe correction time: 15 mEq/L ÷ 0.5 mEq/L/hr = 30 hours
Total Body Water (TBW) Percentages
Children/Adolescents
60% of body weight
Adult Males
60% of body weight
Adult Females
50% of body weight
Elderly Males (≥65)
50% of body weight
Elderly Females (≥65)
45% of body weight
Sodium Level Classifications
Normal
135-145 mEq/L
Mild Hyponatremia
130-134 mEq/L
Moderate Hyponatremia
125-129 mEq/L
Severe Hyponatremia
< 125 mEq/L
Safety Guidelines
Correction Rate
- • Maximum: 0.5 mEq/L per hour
- • Daily limit: 12 mEq/L per day
- • Slower for chronic hyponatremia
Monitoring
- • Check sodium every 2-4 hours
- • Monitor neurological status
- • Adjust infusion rate accordingly
Complications
- • Osmotic demyelination syndrome
- • Central pontine myelinolysis
- • Permanent neurologic damage
Understanding Sodium Deficit
What is Sodium Deficit?
Sodium deficit is the quantity of sodium missing from a patient's body in the state of hyponatremia, expressed in millimoles (mmol). It represents the amount of sodium needed to restore normal electrolyte balance safely.
Clinical Importance
- •Guides appropriate sodium replacement therapy
- •Prevents overcorrection and complications
- •Helps calculate infusion rates and duration
- •Essential for patient safety in hyponatremia treatment
Calculation Formula
Sodium Deficit = TBW × (Desired Na - Serum Na)