In a patient with hypernatremia, which fluid is preferred for correction, 5% dextrose in water (D5W) or quarter‑strength normal saline (QSD‑1)?

Hypernatremia Fluid Management: D5W vs Quarter-Strength Saline

Direct Recommendation

For hypernatremia correction, 5% dextrose in water (D5W) is the preferred initial fluid choice over quarter-strength normal saline (QSD-1), as it provides pure free water replacement without adding any sodium load that could worsen the hypernatremia. 1

Rationale and Evidence Hierarchy

Primary Fluid Selection

• D5W delivers free water without sodium, making it the optimal choice for correcting hypernatremia by directly addressing the water deficit 1
• The American Society of Nephrology explicitly recommends hypotonic fluids such as D5W as first-line therapy for hypernatremia 1
• Isotonic or near-isotonic solutions (including quarter-strength saline with 38.5 mEq/L sodium) can worsen hypernatremia by adding sodium load, particularly in patients with renal concentrating defects 1
• Once D5W is metabolized, it delivers essentially no renal osmotic load, allowing controlled decrease in plasma osmolality without adding osmotic burden 2

When Quarter-Strength Saline May Be Considered

• Quarter-strength saline (D5 0.25NS) may be appropriate only after initial volume resuscitation when combined glucose and modest sodium replacement are needed 2
• In pediatric maintenance after isotonic resuscitation, D5 0.45NS (half-strength, not quarter-strength) is used when serum sodium is normal or elevated 2
• For pure hypernatremia correction, D5W remains superior as it avoids any additional sodium administration 1, 3

Critical Administration Parameters

Correction Rate

• Limit sodium decrease to 8-10 mEq/L per day for chronic hypernatremia to prevent cerebral edema 1
• The osmolar correction rate must not exceed 3 mOsm/kg/hour during initial correction 2, 1
• Monitor serum sodium every 2-4 hours during the initial correction phase 1

Volume Calculations

• Calculate free water deficit using standard formulae accounting for total body water and desired sodium correction 3
• Adults require 25-30 mL/kg/24h baseline; children require 100 mL/kg/24h for first 10 kg, 50 mL/kg/24h for 10-20 kg, and 20 mL/kg/24h for remaining weight 1
• Account for ongoing losses (urine output, insensible losses) in addition to correcting existing deficit 3

Special Clinical Scenarios

Nephrogenic Diabetes Insipidus

• Patients with NDI are particularly prone to hypernatremic dehydration and require prompt IV rehydration with hypotonic fluids 1
• D5W is specifically appropriate for NDI patients as their dilute urine (very low sodium concentration) matches the hypotonic intravenous fluid 4
• The concern about rapid sodium decrease causing brain edema does not typically apply to NDI patients due to their urinary losses 4

Renal Concentrating Defects

• Patients with renal concentrating defects will maintain or worsen hypernatremia if given isotonic fluids (including quarter-strength saline in some cases) 1
• These patients specifically require hypotonic fluid replacement with D5W or 0.45% saline 1

Critical Pitfalls to Avoid

Never Use These Approaches

• Do not use isotonic saline (0.9% NaCl) as initial therapy - it will worsen hypernatremia by adding sodium load 1
• Do not administer D5W as a bolus - this risks rapid sodium decrease and cerebral edema 4
• Avoid too rapid correction of chronic hypernatremia, which causes brain edema due to volume regulation mechanisms that have restored brain volume to normal 3, 5

Volume Status Assessment

• Always assess volume status (hypovolemic, euvolemic, hypervolemic) before initiating treatment 1
• If hypovolemic shock is present, initial resuscitation requires isotonic crystalloids (10-20 mL/kg), then switch to D5W for hypernatremia correction 2
• Isotonic fluids are appropriate for acute fluid resuscitation in hypovolemic shock, but this is exceedingly rare in hypernatremic dehydration as intravascular volume is relatively preserved 4

Monitoring Protocol

• Check serum sodium every 2-4 hours initially 1
• Monitor serum osmolality frequently to ensure change does not exceed 3 mOsm/kg/hour 2, 1
• Assess cardiac, renal, and mental status continuously during treatment 1
• Consider urinary catheter placement to monitor diuresis accurately 4
• In patients with renal or cardiac compromise, perform more frequent reassessments to prevent pulmonary edema 2

Comparative Effectiveness Data

• Recent retrospective cohort data showed parenteral D5W decreased serum sodium by 2.25 mEq/L per liter of treatment fluid in ICU patients with hypernatremia 6
• Both D5W and enteral free water are effective, but parenteral D5W was slightly more effective at lowering serum sodium levels 6