What is the treatment for hypernatremia?

Treatment of Hypernatremia

The treatment of hypernatremia requires correction of the underlying cause and careful administration of hypotonic fluids, with a recommended correction rate not exceeding 8-10 mmol/L per day for chronic hypernatremia to avoid neurological complications. 1

Classification and Assessment

Hypernatremia (serum sodium >145 mmol/L) can be classified based on:

1. Duration:

   • Acute: <48 hours
   • Chronic: >48 hours

2. Severity:

   • Mild to moderate
   • Severe (typically >160 mmol/L)

3. Volume status:

   • Hypovolemic: Water and sodium loss with greater water loss
   • Euvolemic: Pure water loss (e.g., diabetes insipidus)
   • Hypervolemic: Excessive sodium gain 2

Treatment Algorithm

Step 1: Determine Volume Status and Chronicity

• Hypovolemic hypernatremia:

  • Signs: Decreased skin turgor, dry mucous membranes, orthostatic hypotension
  • Urine sodium typically <20 mmol/L

• Euvolemic hypernatremia:

  • Signs: Normal vital signs, no edema
  • Consider diabetes insipidus (central or nephrogenic)

• Hypervolemic hypernatremia:

  • Signs: Edema, elevated blood pressure
  • Usually due to excessive sodium administration

Step 2: Calculate Water Deficit

Water deficit (L) = Total body water × [(Current Na⁺/140) - 1]

• Total body water ≈ 0.6 × weight (kg) for men
• Total body water ≈ 0.5 × weight (kg) for women

Step 3: Determine Correction Rate

• For acute hypernatremia (<48 hours):

  • Can correct more rapidly
  • Consider hemodialysis for severe cases 1

• For chronic hypernatremia (>48 hours):

  • Correct by no more than 8-10 mmol/L per day 1
  • Monitor serum sodium every 2-4 hours initially

Step 4: Choose Appropriate Fluids

• Hypovolemic hypernatremia:

  • Initial fluid: 0.9% saline to restore hemodynamic stability
  • Then switch to hypotonic fluids (0.45% saline or 5% dextrose)

• Euvolemic hypernatremia:

  • 5% dextrose in water or 0.45% saline
  • For central diabetes insipidus: desmopressin (Minirin) 1

• Hypervolemic hypernatremia:

  • Loop diuretics plus 5% dextrose
  • Consider hemodialysis for severe cases

Special Considerations

Pediatric Patients

• More susceptible to rapid changes in serum sodium
• ESPGHAN/ESPEN guidelines recommend a reduction rate of 10-15 mmol/L/24h 3

Critically Ill Patients

• Hypernatremia is common in ICU and associated with increased mortality 4
• Careful monitoring of fluid status and electrolytes is essential

Neurological Monitoring

• Monitor for signs of cerebral edema during correction
• Symptoms include headache, altered mental status, seizures, or focal neurological deficits

Common Pitfalls to Avoid

1. Overly rapid correction of chronic hypernatremia can lead to cerebral edema, seizures, and neurological injury 3

2. Failure to identify and treat the underlying cause (e.g., diabetes insipidus, excessive sodium intake)

3. Inappropriate fluid choice based on volume status

4. Inadequate monitoring during correction

5. Failure to adjust for ongoing losses (e.g., gastrointestinal, renal, insensible)

The management of hypernatremia requires careful attention to the rate of correction and frequent monitoring of serum sodium levels. The goal is to correct the electrolyte abnormality while avoiding complications from overly rapid correction, particularly in cases of chronic hypernatremia.