How is hypernatremia managed with D5 (5% dextrose in water)?

Management of Hypernatremia with D5W

For treating hypernatremia, 5% dextrose in water (D5W) should be used as first-line therapy, as it provides free water without additional sodium load, effectively addressing the water deficit that defines hypernatremia. 1

Pathophysiology and Rationale

Hypernatremia (serum sodium >145 mEq/L) represents a water deficit relative to sodium content. D5W is the ideal solution because:

• It delivers free water once the dextrose is metabolized
• It contains no sodium, allowing for correction of the relative water deficit
• Salt-containing solutions like 0.9% NaCl should be avoided as they can worsen hypernatremia 2, 1

Calculation of Fluid Requirements

Initial Rate Calculation

1. For children:

   • First 10 kg: 100 ml/kg/24h (4 ml/kg/h)
   • 10-20 kg: additional 50 ml/kg/24h (2 ml/kg/h)
   • Above 20 kg: additional 25 ml/kg/24h (1 ml/kg/h) 2

2. For adults:

   • 25-30 ml/kg/24h 2, 1

Water Deficit Calculation

Water deficit (L) = [(Current Na⁺ - 140)/140] × Total body water

• Total body water ≈ 0.6 × weight (kg) for adults
• Total body water ≈ 0.7 × weight (kg) for children

Rate of Correction

• Maximum correction rate: 8 mEq/L in 24 hours for standard patients 1
• High-risk patients (alcoholism, malnutrition, liver disease): 4-6 mEq/L in 24 hours 1

Monitoring Protocol

• Check serum sodium every 4-6 hours during active correction
• Adjust fluid rate based on sodium levels and clinical response
• Monitor for signs of cerebral edema (headache, nausea, altered mental status)
• Assess fluid status regularly (vital signs, urine output, weight) 1

Special Considerations

Acute vs. Chronic Hypernatremia

• Acute hypernatremia (<48 hours): Can tolerate slightly faster correction
• Chronic hypernatremia (>48 hours): Requires slower correction to prevent cerebral edema

Concomitant Conditions

• Diabetes insipidus: May require additional interventions (e.g., desmopressin) 3
• Hyperglycemic states: Correct glucose first, then address hypernatremia 3, 4
• Renal failure: May require modified approach with careful monitoring 5

Common Pitfalls to Avoid

• Using salt-containing solutions (e.g., 0.9% NaCl), which increase renal osmotic load and can worsen hypernatremia 2
• Correcting sodium too rapidly, which can lead to cerebral edema and neurological complications 1, 6
• Inadequate monitoring of serum sodium levels during correction
• Ignoring the underlying cause of hypernatremia

Algorithm for D5W Administration

1. Calculate water deficit and maintenance requirements
2. Initiate D5W at calculated rate
3. Monitor serum sodium every 4-6 hours
4. Adjust rate to achieve target correction of ≤8 mEq/L/24h
5. Once serum sodium approaches normal range (135-145 mEq/L), transition to maintenance fluids

By following this evidence-based approach with D5W, hypernatremia can be safely and effectively corrected while minimizing the risk of complications.