Calculation of Milliequivalents in 100 mL of NaCl Solution
100 mL of 0.9% NaCl solution contains 15.4 milliequivalents (mEq) of sodium and 15.4 mEq of chloride, for a total of 15.4 mEq of NaCl.
Calculation Method
To determine the milliequivalent content:
- 0.9% NaCl solution = 0.9 grams of NaCl per 100 mL
- Molecular weight of NaCl = 58.5 g/mol
- Valence of both Na+ and Cl- = 1
Formula: mEq = (grams × valence) / molecular weight × 1000
Calculation:
- mEq = (0.9 g × 1) / 58.5 g/mol × 1000
- mEq = 15.4 mEq
Since NaCl dissociates into equal amounts of Na+ and Cl-, you get 15.4 mEq of sodium and 15.4 mEq of chloride per 100 mL.
Clinical Context
This calculation is fundamental when prescribing 0.9% NaCl (normal saline) for intravenous fluid therapy. The solution contains 154 mEq/L of sodium and 154 mEq/L of chloride, which is notably higher than physiological plasma chloride concentrations 1.
Important Considerations:
Hyperchloremic acidosis risk: The supraphysiologic chloride content in 0.9% NaCl can cause hyperchloremic metabolic acidosis and may adversely affect renal perfusion through chloride-induced renal artery vasoconstriction 2, 3
Volume considerations: While guidelines don't provide Grade 1 recommendations for specific crystalloid types in hemorrhagic shock, high-volume chloride-rich solutions (>5000 mL) have been associated with increased mortality and renal complications 4
Balanced solutions alternative: Current evidence increasingly favors balanced crystalloid solutions over 0.9% NaCl for large-volume resuscitation, though 0.9% NaCl remains widely used 4