Preparing D5 Lactated Ringer's Solution
No, you do not add one amp of D50 to a liter bag of LR to make D5 LR—this would create an incorrect concentration. To prepare D5 LR properly, you would need to add 50 grams of dextrose to 1 liter of lactated Ringer's solution, which equals 100 mL of D50 (50% dextrose), not a single standard 50 mL ampule 1.
The Mathematics Behind the Preparation
- D5 solution contains 5 grams of dextrose per 100 mL (5% concentration) 1
- For 1 liter (1000 mL), you need 50 grams total dextrose 1
- D50 contains 0.5 grams per mL 1
- Therefore: 50 grams ÷ 0.5 grams/mL = 100 mL of D50 required 1
Clinical Reality: Use Commercial Preparations
In practice, D5 lactated Ringer's is available as a commercial preparation and should be ordered from pharmacy rather than prepared at bedside 2. The commercially prepared D5 LR contains:
- 5 g/dL dextrose
- 130 mEq/L sodium
- 109 mEq/L chloride
- 4 mEq/L potassium
- 3 mEq/L calcium
- 28 mEq/L lactate buffer
- Osmolarity of 273 mOsm/L 2
Why D5 LR Matters Clinically
- The American Academy of Pediatrics recommends isotonic solutions with 5% dextrose for maintenance IV fluids in pediatric patients to prevent both hyponatremia and hypoglycemia 3
- D5 LR is preferred over D5 normal saline because balanced crystalloids like LR reduce the risk of hyperchloremic acidosis and acute kidney injury compared to normal saline 3, 4
- The dextrose component is rapidly metabolized and does not contribute significantly to osmolarity calculations 2
Critical Pitfalls to Avoid
- Never attempt bedside mixing of concentrated dextrose into large volume bags—this risks calculation errors, contamination, and incorrect final concentrations 1
- If D5 LR is unavailable commercially, consult pharmacy for proper sterile compounding rather than attempting manual preparation 2
- Remember that D50 is hypertonic (2.53 mOsm/mL) and intended for central venous administration or emergency hypoglycemia treatment, not routine dilution 1