What is the treatment for hypernatremia?

Treatment of Hypernatremia

The treatment of hypernatremia requires hypotonic fluid administration with correction rates not exceeding 8-10 mmol/L/day for chronic hypernatremia (>48 hours), while addressing the underlying cause. 1, 2

Assessment and Classification

First, determine the duration and severity of hypernatremia:

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

Then, assess volume status to guide treatment:

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

Treatment Algorithm

1. Hypovolemic Hypernatremia

• First-line: Isotonic saline (0.9% NaCl) initially to restore hemodynamic stability
• Second-line: Switch to hypotonic fluids (0.45% NaCl or 5% dextrose) once hemodynamically stable 3
• Address underlying cause: Stop diuretics, treat gastrointestinal losses, etc.

2. Euvolemic Hypernatremia

• First-line: Hypotonic fluids (0.45% NaCl or 5% dextrose in water)
• For diabetes insipidus:
  • Central: Desmopressin (DDAVP) 1
  • Nephrogenic: Treat underlying cause, consider thiazide diuretics

3. Hypervolemic Hypernatremia

• First-line: Loop diuretics to promote sodium excretion
• Second-line: Hypotonic fluids if needed
• Address underlying cause: Discontinue hypertonic solutions, treat hyperaldosteronism

Calculation of Water Deficit

Calculate the free water deficit:

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

Where total body water = 0.6 × weight (kg) for men and 0.5 × weight (kg) for women

Correction Rate

• Acute hypernatremia (<24 hours): Can correct more rapidly, consider hemodialysis for severe cases 1
• Chronic hypernatremia (>48 hours): Do not exceed 8-10 mmol/L/day correction rate to prevent cerebral edema 1, 2

Monitoring

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

Special Considerations

• ICU patients: Hypernatremia is associated with increased mortality; careful sodium and water balance management is crucial 4
• Neurological patients: Rapid changes in sodium concentration may have deleterious consequences; close laboratory monitoring is essential 1
• Diabetes insipidus: May require desmopressin in addition to fluid replacement 1

Pitfalls to Avoid

• Correcting chronic hypernatremia too rapidly can cause cerebral edema
• Using isotonic fluids alone for hypernatremia will not effectively lower sodium levels
• Failing to identify and treat the underlying cause will lead to recurrence
• Inadequate monitoring during correction can lead to complications

Remember that the rate of correction is critical and must be adjusted based on the rapidity of hypernatremia development. For chronic hypernatremia, a slow correction rate (no more than 0.4 mmol/L/hour or 8-10 mmol/L/day) is recommended to prevent neurological complications 2.