How is hypernatremia treated?

Treatment of Hypernatremia

The treatment of hypernatremia should be based on identifying the underlying cause, distinguishing between acute and chronic hypernatremia, and carefully correcting water deficits while avoiding overly rapid correction that could lead to cerebral edema and neurological complications. 1

Assessment and Classification

Before initiating treatment, proper evaluation is essential:

1. Exclude pseudohypernatremia
2. Confirm glucose-corrected sodium concentrations
3. Determine extracellular volume status:
   • Hypovolemic hypernatremia
   • Euvolemic hypernatremia
   • Hypervolemic hypernatremia
4. Measure urine sodium levels and osmolality

Treatment Algorithm

Step 1: Identify the Underlying Cause

• Water loss (gastrointestinal, renal, skin, respiratory)
• Inadequate water intake
• Diabetes insipidus
• Excessive sodium intake

Step 2: Distinguish Between Acute and Chronic Hypernatremia

• Acute (developed within 48 hours): Can be corrected more rapidly
• Chronic (developed over >48 hours): Requires slower correction

Step 3: Determine Water Deficit and Rate of Correction

Calculate total body water deficit:

• Water deficit = Current TBW × [(Current Na⁺/140) - 1]
• Current TBW (Total Body Water) = Weight × 0.6 (for men) or 0.5 (for women)

Correction rates:

• For chronic hypernatremia: Decrease serum sodium by no more than 10 mmol/L/day 1
• For acute hypernatremia: Can correct more rapidly but still monitor closely

Step 4: Select Appropriate Replacement Solution

Based on volume status:

• Hypovolemic hypernatremia:

  • Begin with isotonic saline (0.9% NaCl) to restore volume
  • Then switch to hypotonic solutions (0.45% NaCl or 5% dextrose)

• Euvolemic hypernatremia:

  • Hypotonic solutions (0.45% NaCl or 5% dextrose)
  • Water replacement orally if possible

• Hypervolemic hypernatremia:

  • Loop diuretics to promote sodium excretion
  • Hypotonic fluids with careful monitoring

Step 5: Adjust Treatment Schedule and Monitor

• Check serum sodium every 2-4 hours initially
• Adjust fluid administration rate based on sodium correction rate
• Monitor for signs of cerebral edema (headache, altered mental status, seizures)

Step 6: Consider Additional Therapy for Specific Causes

• Diabetes insipidus:
  • Central: Desmopressin (DDAVP)
  • Nephrogenic: Treat underlying cause, thiazide diuretics, NSAIDs, amiloride

Special Considerations

Neurological Complications

• Overly rapid correction of chronic hypernatremia can lead to cerebral edema 2
• Brain adaptative mechanisms to changes in osmolality take time to develop and reverse 3

High-Risk Populations

• Elderly patients
• Infants and young children
• Critically ill patients
• Patients with neurological disorders

Pitfalls to Avoid

1. Correcting too rapidly: Can cause cerebral edema and neurological damage
2. Failing to identify and treat the underlying cause
3. Inadequate monitoring during correction
4. Using inappropriate fluids based on volume status
5. Not accounting for ongoing fluid losses in calculations

By following this structured approach to hypernatremia management, clinicians can effectively correct this potentially dangerous electrolyte disorder while minimizing the risk of complications.