Carbohydrate Calculation for D5 Infusion
A patient receiving D5 (5% dextrose) at 125 mL/hour will receive 150 grams of carbohydrates in 24 hours.
Mathematical Calculation
The calculation is straightforward using the composition of D5 solution:
- D5 contains 5 grams of dextrose per 100 mL 1
- At 125 mL/hour × 24 hours = 3,000 mL total volume in 24 hours
- Total carbohydrates = (3,000 mL ÷ 100 mL) × 5 grams = 150 grams 1
Alternatively, this can be calculated as:
- 125 mL/hour × 0.05 g/mL = 6.25 grams of dextrose per hour 2
- 6.25 grams/hour × 24 hours = 150 grams total carbohydrates 2
Clinical Context and Energy Provision
This infusion provides approximately 600 kcal of energy over 24 hours (150 grams × 4 kcal/gram), which represents partial nutritional support but is insufficient as sole nutrition 1. This rate delivers more carbohydrate than the standard maintenance rate of 100 mL/hour, which provides only 120 grams over 24 hours 2.
Insulin Coverage Considerations
For diabetic patients receiving this dextrose load:
- The American Diabetes Association recommends approximately 1 unit of insulin for every 10-15 grams of carbohydrate 1
- A patient receiving 150 grams of carbohydrates would require roughly 10-15 units of insulin per 24 hours for nutritional coverage 1
- Blood glucose monitoring every 1-2 hours is essential when administering dextrose-containing fluids to avoid both hypoglycemia and hyperglycemia 1, 2
Important Clinical Caveats
Hyperglycemia risk: Even in non-diabetic patients, D5 infusions can cause transient hyperglycemia, with studies showing mean serum glucose rises of approximately 9 mg/dL above fasting levels at 100 mL/hour 3. At 125 mL/hour, expect slightly higher glucose elevations 3.
Thiamine administration: Thiamine should be administered prior to starting glucose infusion to reduce the risk of Wernicke's encephalopathy when using dextrose as part of nutritional support 1.