What does D5 LR (5% dextrose in Lactated Ringer's solution) mean?

D5 LR: Definition and Composition

D5 LR stands for 5% dextrose in Lactated Ringer's solution—a combination intravenous fluid that contains both glucose (50 grams per liter) and the electrolyte components of Lactated Ringer's solution (sodium 130 mEq/L, potassium 4 mEq/L, chloride 109 mEq/L, calcium 3 mEq/L, and lactate 28 mEq/L). 1

Clinical Composition Details

• Dextrose component: The "D5" indicates 5% dextrose, providing 50 grams of glucose per liter of solution 2
• Lactated Ringer's base: Contains balanced electrolytes that more closely resemble plasma composition compared to normal saline, with a physiologic Na+:Cl- ratio 3
• Osmolarity: The solution has an osmolarity of approximately 525 mOsm/L (combining the ~273-277 mOsm/L from Lactated Ringer's and ~252 mOsm/L from 5% dextrose) 3
• Functional tonicity: While initially hypertonic, D5 LR becomes hypotonic once the glucose is metabolized by cells, as the dextrose component is rapidly taken up 3

Key Clinical Characteristics

• Potassium content: The solution already contains 4 mEq/L of potassium from the Lactated Ringer's base, which must be accounted for when calculating total potassium administration 3
• Lactate buffer: Contains 27-28 mEq/L of lactate, which is metabolized to bicarbonate in the liver and does not falsely elevate serum lactate levels when infused at standard resuscitation rates 2
• Calcium content: Contains approximately 3 mEq/L of calcium, which can interact with certain medications 3

Primary Clinical Uses

D5 LR is specifically recommended for maintenance fluid replacement in patients with severe dehydration who cannot tolerate oral intake, particularly when ongoing losses need replacement. 1

• For severe dehydration with inability to drink: Administer 5% dextrose 0.25 normal saline with 20 mEq/L potassium chloride intravenously (D5 LR provides a similar balanced alternative) 1
• For hypernatremic dehydration: The hypotonic nature after glucose metabolism makes it appropriate for replacing free water losses, particularly in conditions like nephrogenic diabetes insipidus 1

Critical Contraindications

D5 LR should be absolutely avoided in patients with severe head trauma or traumatic brain injury due to its hypotonic nature after glucose metabolism, which can worsen cerebral edema. 1, 3

• In brain-injured patients, 0.9% saline is the crystalloid of choice as it remains isotonic 3
• Hypotonic solutions like D5 LR can cause fluid shift into damaged cerebral tissue, worsening intracranial pressure 1

Important Clinical Pitfalls

• Cardiac arrest resuscitation: Dextrose-containing solutions like D5 LR should never be used during cardiac arrest resuscitation, as hyperglycemia during arrest significantly worsens neurologic outcomes and increases mortality 4
• Bolus administration risk: D5 LR should not be administered as a rapid bolus in hypernatremic patients due to risk of rapid sodium decrease and brain edema; controlled infusion rates are essential 1
• Lactate monitoring: The lactate in D5 LR does not interfere with serum lactate measurements when infused at 1 L/hour or less 2