What is the amount of sodium in millimoles in a 3% sodium chloride (NaCl) 500ml solution?

Sodium Content in 3% Sodium Chloride 500ml Solution

A 3% sodium chloride (NaCl) 500ml solution contains 513 mmol of sodium. 1

Calculation Breakdown

• 3% sodium chloride solution means 3 grams of NaCl per 100ml of solution
• In 500ml solution, this equals 15 grams of NaCl (3g × 5)
• The molecular weight of sodium (Na) is 23g/mol
• The molecular weight of chloride (Cl) is 35.5g/mol
• The molecular weight of NaCl is 58.5g/mol (23 + 35.5) 1
• To calculate mmol of sodium:
  • 15g NaCl × (23g Na ÷ 58.5g NaCl) = 5.9g Na
  • 5.9g Na ÷ 23g/mol = 256.5 mmol Na per 500ml

Sodium Concentration in Different NaCl Solutions

• 0.9% NaCl (normal saline) contains 154 mmol/L of sodium (or 77 mmol in 500ml) 1
• 3% NaCl contains 513 mmol/L of sodium (or 256.5 mmol in 500ml)
• 23.4% NaCl contains 4000 mmol/L of sodium (or 2000 mmol in 500ml) 2

Clinical Applications of 3% Sodium Chloride

• 3% sodium chloride is a hypertonic solution primarily used for treating:

  • Severe hyponatremia with neurological symptoms 3
  • Cerebral edema 2
  • Increased intracranial pressure 2

• For hyponatremic encephalopathy, a protocol of 500ml of 3% sodium chloride over 6 hours has been shown to be effective and safe 3

• Bolus therapy with 3% NaCl (100-250ml) is effective for initial treatment of severe hyponatremia 4

Important Considerations

• Hypertonic saline solutions should be administered with caution due to risk of:

  • Rapid correction of sodium levels leading to osmotic demyelination syndrome 3
  • Fluid overload in susceptible patients 5
  • Phlebitis when administered peripherally 2

• The goal of therapy with 3% NaCl is typically to increase serum sodium by 5-6 mmol/L in the first 4-6 hours to reverse neurological symptoms 3, 4

• The rate of sodium correction should not exceed 10 mmol/L in the first 24 hours to avoid neurological complications 3, 4