From the Research
A bag of normal saline (NS) contains significantly more chloride than a bag of D5W/half NS, with 154 mEq of chloride in NS versus 77 mEq of chloride in D5W/half NS. This difference is due to the composition of NS as a 0.9% sodium chloride solution, providing an isotonic concentration of both sodium and chloride ions, whereas D5W/half NS is a combination of 5% dextrose in water with half-strength (0.45%) sodium chloride, resulting in half the chloride concentration 1.
The clinical importance of this distinction lies in managing patients with electrolyte imbalances, acid-base disorders, or renal impairment. The higher chloride content in NS can potentially contribute to hyperchloremic metabolic acidosis with large volume administration, as seen in studies where balanced electrolyte solutions were compared to normal saline 2, 3, 1. In contrast, D5W/half NS provides less chloride load but adds 50g of dextrose per liter, which can affect blood glucose levels.
When selecting between these fluids, it is crucial to consider the patient's chloride status, acid-base balance, and glucose management needs. A recent study published in 2025 found that using balanced multielectrolyte solutions instead of normal saline resulted in a significantly more physiological serum chloride level, associated with multiple clinical benefits, including less systemic inflammatory response syndrome and increased organ failure-free days 1.
Key points to consider:
- NS contains 154 mEq of chloride per liter
- D5W/half NS contains 77 mEq of chloride per liter
- Higher chloride content in NS can contribute to hyperchloremic metabolic acidosis
- D5W/half NS provides less chloride load but adds 50g of dextrose per liter
- Patient's chloride status, acid-base balance, and glucose management needs should guide fluid selection 1, 4.