Treatment of Hypernatremia (168 mmol/L)
For severe hypernatremia of 168 mmol/L, treatment should focus on gradual correction with hypotonic fluids at a rate not exceeding 8-10 mmol/L per day to prevent neurological complications.
Initial Assessment and Management
Determine duration of hypernatremia:
- Acute (<48 hours): Can correct more rapidly
- Chronic (>48 hours): Must correct slowly at ≤8-10 mmol/L/day
Assess volume status:
- Hypovolemic: Most common cause of hypernatremia
- Euvolemic: Often due to diabetes insipidus
- Hypervolemic: Rare, usually from excessive sodium administration
Treatment Protocol
Step 1: Calculate Water Deficit
- Water deficit (L) = Total body water × [(Current Na⁺/140) - 1]
- Total body water ≈ 0.6 × weight (kg) for men; 0.5 × weight (kg) for women
Step 2: Choose Appropriate Fluid
- 5% Dextrose in water (D5W): Free water replacement
- 0.45% Saline: Hypotonic solution for patients requiring some sodium
- 0.9% Saline: Only if patient is severely hypovolemic, then switch to hypotonic fluids
Step 3: Determine Rate of Correction
- For chronic hypernatremia (>48 hours), target correction rate: 8-10 mmol/L/day 1, 2
- For acute hypernatremia (<24 hours), faster correction may be considered
Step 4: Monitor Closely
- Check serum sodium every 2-4 hours initially
- Adjust fluid rate based on sodium measurements
- Monitor for neurological symptoms
- Track fluid input/output and daily weights
Special Considerations
- Avoid overly rapid correction: This can lead to cerebral edema and neurological damage 2
- Hemodialysis: Consider for acute severe hypernatremia when rapid correction is needed 2
- Address underlying cause:
- Diabetes insipidus: Consider desmopressin (DDAVP)
- Excessive water loss: Control fever, hyperventilation, diarrhea
- Iatrogenic causes: Adjust medication regimen
Pitfalls to Avoid
- Do not correct too rapidly: Never exceed 10 mmol/L/day for chronic hypernatremia
- Do not use hypertonic solutions: These will worsen hypernatremia
- Do not neglect ongoing losses: Continue to replace ongoing fluid losses
- Do not overlook neurological status: Monitor for changes in mental status during correction
Follow-up Management
- Once serum sodium begins to normalize, transition to oral fluids if patient is able to drink
- Continue monitoring serum sodium daily until stable
- Implement preventive measures to avoid recurrence
This approach prioritizes patient safety by preventing neurological complications while effectively treating the dangerous electrolyte imbalance.