What fluids should be ordered for a patient with hypernatremia?

Management of Hypernatremia (Serum Sodium 149 mEq/L)

For a patient with hypernatremia (serum sodium 149 mEq/L), hypotonic fluids such as 5% dextrose in water (D5W) should be administered as the primary treatment to safely correct the sodium imbalance.

Understanding Hypernatremia

Hypernatremia is defined as a serum sodium level above 145 mEq/L 1. At 149 mEq/L, this patient has mild hypernatremia that requires prompt intervention to prevent progression to more severe levels that could lead to neurological complications.

Fluid Selection Principles

Preferred Fluids:

• 5% Dextrose in Water (D5W) is the first-line fluid choice 2, 3
  • D5W provides free water without adding sodium load
  • Dextrose is metabolized, leaving only free water to dilute serum sodium

Fluids to Avoid:

• Normal saline (0.9% NaCl) should be avoided 2
  • Contains approximately 300 mOsm/kg H₂O
  • Can worsen hypernatremia as it adds more sodium

Rate of Correction

• Correct sodium levels gradually over 48-72 hours 4
• Target correction rate: no more than 8 mEq/L per day 5
• Too rapid correction can lead to cerebral edema 4

Special Considerations

Volume Status Assessment:

• If patient is hypovolemic: Begin with careful D5W administration
• If patient is euvolemic: D5W at maintenance rate
• If patient is hypervolemic: Consider adding a diuretic while providing D5W

Monitoring Requirements:

• Check serum sodium every 4-6 hours initially
• Monitor for signs of cerebral edema (headache, altered mental status)
• Track fluid intake and output
• Assess for clinical improvement

Additional Management Steps

1. Identify and treat underlying cause:

   • Limited water access
   • Diabetes insipidus
   • Excessive water loss (diarrhea, vomiting)
   • Fever or heat stroke
   • Medication effects

2. For patients with renal impairment:

   • Calculate the amount of D5W needed based on effluent volume if on CRRT 5
   • Consider nephrology consultation for complex cases

Pitfalls to Avoid

• Using isotonic or hypertonic fluids that can worsen hypernatremia
• Correcting sodium levels too rapidly
• Failing to identify and address the underlying cause
• Not monitoring sodium levels frequently during correction

In severe cases (sodium >170 mEq/L) or when neurological symptoms are present, more aggressive management in an intensive care setting may be required 4.