Correction of Hypernatremia: Fluid Selection and Management
For correcting hypernatremia, hypotonic fluids such as D5W (5% dextrose in water) or hypotonic saline (0.2-0.45% NaCl) should be used as the primary treatment, with the specific choice depending on the patient's volume status and the chronicity of the condition. 1
Fluid Selection Based on Volume Status
Hypovolemic Hypernatremia
- Initial fluid: Begin with isotonic 0.9% saline to restore intravascular volume
- Subsequent fluid: Switch to hypotonic solutions (D5W or 0.45% NaCl) once hemodynamic stability is achieved 2, 3
Euvolemic Hypernatremia
- Primary fluid: D5W (5% dextrose in water) is the fluid of choice
- Alternative: 0.45% NaCl (half-normal saline) if some sodium replacement is needed 1, 3
Hypervolemic Hypernatremia
- Primary fluid: D5W to correct free water deficit
- Additional measure: Consider adding diuretics to promote sodium excretion 3
Rate of Correction
The rate of correction depends on the chronicity of hypernatremia:
- Acute hypernatremia (<48 hours): Can be corrected more rapidly, but not exceeding 1 mmol/L/hour 4
- Chronic hypernatremia (>48 hours): Should be corrected slowly at a rate of 8-10 mmol/L/day to prevent cerebral edema 1, 4
Monitoring During Correction
- Check serum sodium levels every 2-4 hours initially during treatment 1
- Monitor for signs of cerebral edema (headache, altered mental status, seizures)
- Adjust fluid rate based on sodium correction rate and clinical response
Special Considerations
- For diabetic patients with hyperglycemic hyperosmolar state, switch to D5W with appropriate sodium concentration (0.2-0.45% NaCl) once blood glucose reaches target levels 1
- In patients with renal failure, hemodialysis may be an effective option for rapid normalization of serum sodium in acute cases 4
- For patients with diabetes insipidus causing hypernatremia, desmopressin (Minirin) may be indicated in addition to fluid replacement 4
Common Pitfalls to Avoid
- Overly rapid correction of chronic hypernatremia can lead to cerebral edema and neurological complications
- Inadequate monitoring of serum sodium during treatment
- Failure to identify and treat the underlying cause of hypernatremia
- Using isotonic fluids alone for euvolemic or hypervolemic hypernatremia, which may be insufficient to correct the free water deficit
Remember that hypernatremia reflects a deficit of free water relative to sodium, and treatment should focus on replacing this deficit while addressing the underlying cause.