What is the difference between Dextrose Normal Saline (DNS) and 5% dextrose in terms of patient management?

DNS vs 5% Dextrose: Key Clinical Differences

DNS (Dextrose Normal Saline) contains both sodium chloride and dextrose, delivering a significant renal osmotic load, while 5% dextrose alone provides free water without osmotic burden—making 5% dextrose the preferred choice for hypernatremic dehydration and DNS appropriate when both glucose and sodium replacement are needed.

Composition Differences

DNS (Dextrose Normal Saline)

• Contains 50 grams of dextrose per liter (5% concentration) plus 0.9% sodium chloride (9 grams NaCl/L) 1
• Delivers tonicity of approximately 300 mOsm/kg H₂O from the sodium chloride component 2
• Provides both glucose supplementation and sodium replacement simultaneously 1

5% Dextrose Alone

• Contains only 5 grams of dextrose per 100 mL (50 grams per liter) with no sodium 1
• Delivers essentially no renal osmotic load once dextrose is metabolized 2
• Functions as free water replacement 2

Critical Clinical Applications

When to Use 5% Dextrose (NOT DNS)

Hypernatremic dehydration requires 5% dextrose, not DNS or normal saline-containing solutions 2:

• Salt-containing solutions must be avoided in hypernatremic states because their tonicity (~300 mOsm/kg) exceeds typical urine osmolality, requiring approximately 3 liters of urine to excrete the osmotic load from 1 liter of isotonic fluid, risking serious worsening of hypernatremia 2
• 5% dextrose allows slow, controlled decrease in plasma osmolality without adding osmotic burden 2
• This is particularly critical in nephrogenic diabetes insipidus patients with hypernatremic dehydration 2

Geriatric dehydration management 2:

• Subcutaneous rehydration can use 5% dextrose solutions effectively 2
• Options include half-normal saline with 5% glucose, or 5% dextrose with 4 g/L NaCl 2

When to Use DNS (Dextrose Normal Saline)

Isonatremic dehydration in children with diarrhea 3:

• Best treated with 5% dextrose in 0.45% saline (half-normal saline) containing 20 mEq/L KCl over 24 hours 3
• For severe dehydration, initial resuscitation uses 0.9% saline (60-100 mL/kg over 2-4 hours), then switch to maintenance fluids 3

Diabetic ketoacidosis (DKA) management 4:

• When serum glucose reaches 250 mg/dL during DKA treatment, fluids should be changed to include dextrose (D5 or D10) with 0.45-0.75% NaCl plus appropriate potassium 4
• This prevents hypoglycemia while continuing insulin therapy and provides necessary sodium replacement 4

Pediatric hypoglycemia prevention 4:

• Infants dependent on IV fluids and at risk for hypoglycemia benefit from D10 normal saline to meet glucose requirements of 4-6 mg/kg/min 4

Medication vehicle 1:

• DNS serves as a vehicle for medication administration, particularly vasopressors 1

Important Clinical Pitfalls

Hyperglycemia Risk with DNS

Even 500 mL of DNS causes significant transient hyperglycemia in non-diabetic surgical patients 5:

• 72% of patients receiving DNS had plasma glucose >10 mmol/L at 15 minutes post-infusion 5
• DNS is not required to prevent hypoglycemia in elective surgery despite average fasting times of 13 hours 5

Electrolyte Disturbances

Using saline-based diluents (including DNS) instead of 5% dextrose increases risk of hypernatremia and hyperchloremia 6:

• Hypernatremia incidence: 27.3% with saline vs 14.6% with D5W (adjusted OR 2.43) 6
• Hyperchloremia incidence: 36.9% with saline vs 20.4% with D5W (adjusted OR 2.09) 6

Ketone Clearance in Gastroenteritis

DNS provides superior ketone clearance compared to normal saline alone in dehydrated children with gastroenteritis 7:

• Greater reduction in serum ketones at 1 hour (1.2 vs 0.1 mmol/L) and 2 hours (1.9 vs 0.3 mmol/L) 7
• However, this did not translate to reduced hospitalization rates 7

Practical Decision Algorithm

For hypernatremia or pure water deficit: Use 5% dextrose alone 2

For isonatremic dehydration requiring both water and sodium: Use DNS or dextrose in half-normal saline 3

For DKA after initial resuscitation (glucose <250 mg/dL): Switch to DNS or D10 with 0.45-0.75% saline 4

For pediatric maintenance fluids with hypoglycemia risk: Use D10 normal saline 4

For medication dilution in critically ill patients: Consider 5% dextrose to minimize electrolyte disturbances 6

For elective surgery: Avoid DNS; use non-dextrose crystalloids to prevent unnecessary hyperglycemia 5