No, You Should Not Use Normal Saline to Dilute 25% Dextrose
Do not use normal saline as a diluent for dextrose solutions—use sterile water instead. This is standard pharmaceutical practice based on osmolarity principles and established guidelines for preparing dextrose solutions.
Why Sterile Water is Required
When diluting concentrated dextrose solutions (like D25W to make D10W), sterile water is the appropriate diluent because:
Osmolarity control: Dextrose solutions are designed to have specific osmolarities. Using normal saline (which already contains 154 mEq/L sodium and has an osmolarity of 308 mOsm/L) would create an inappropriately hypertonic solution 1
Sodium loading: Adding saline to dextrose would deliver unintended sodium, which can cause hypernatremia and hyperchloremia—particularly problematic in pediatric and critically ill patients 2, 3
Standard practice: Pediatric emergency guidelines specifically describe preparing D10W by diluting D25W or D50W with appropriate volumes, implicitly using sterile water as the standard diluent 4
Clinical Evidence Against Using Saline as Diluent
Research demonstrates significant problems when saline is used inappropriately:
Hypernatremia risk: A retrospective study found that using 0.9% saline (rather than D5W) as a drug diluent in ICU patients significantly increased hypernatremia (adjusted OR 2.43) and hyperchloremia (adjusted OR 2.09) 2
Sodium overload: Normal saline used to dilute drugs and keep catheters open was identified as "a major and preventable source of hypernatremia" in ICU patients 3
Fatal complications: When 25% albumin was diluted with sterile water alone (creating hypotonic solution), hemolysis occurred, including one fatal case—demonstrating the critical importance of proper diluent selection 5
Correct Dilution Method
To prepare D10W from D25W:
- Use sterile water for injection as the diluent
- For 0.5-1.0 g/kg dextrose dose: use 2-4 mL/kg of D25W 4
- The resulting solution maintains appropriate osmolarity without adding sodium
Common Pitfall to Avoid
Never confuse the diluent for making dextrose solutions with the choice of maintenance IV fluids. While current pediatric guidelines recommend isotonic fluids (like 0.9% NaCl with dextrose added) for maintenance therapy 6, this refers to commercially prepared or appropriately formulated solutions—not using saline to dilute concentrated dextrose stock.
The pharmaceutical preparation of dextrose solutions requires sterile water to achieve the correct final osmolarity and avoid unintended electrolyte administration.