What is the treatment for hypernatremia?

Treatment of Hypernatremia

The treatment of hypernatremia should focus on identifying the underlying cause, replacing water deficit gradually, and monitoring serum sodium frequently during correction, with a target reduction rate of 8-10 mmol/L/day to prevent cerebral edema. 1

Diagnosis and Assessment

Before initiating treatment, it's essential to:

1. Confirm hypernatremia (serum sodium >145 mmol/L)
2. Assess volume status:
   • Hypovolemic hypernatremia
   • Euvolemic hypernatremia
   • Hypervolemic hypernatremia
3. Determine chronicity:
   • Acute (<48 hours)
   • Chronic (>48 hours)

Treatment Algorithm Based on Volume Status

Hypovolemic Hypernatremia

• Cause: Water and sodium losses with greater water than sodium loss
• Treatment:
  • Initial volume resuscitation with isotonic fluids (0.9% saline) to restore hemodynamic stability
  • Once hemodynamically stable, switch to hypotonic fluids (0.45% saline or 5% dextrose)
  • Calculate free water deficit and replace gradually

Euvolemic Hypernatremia

• Cause: Pure water loss (diabetes insipidus, insensible losses)
• Treatment:
  • Hypotonic fluids (0.45% saline or 5% dextrose in water)
  • For diabetes insipidus: treat underlying cause and consider desmopressin if central DI 2
  • Ensure adequate oral water intake if patient is able

Hypervolemic Hypernatremia

• Cause: Sodium gain exceeds water gain
• Treatment:
  • Loop diuretics to promote sodium excretion
  • Hypotonic fluids if needed
  • Dialysis may be required in severe cases with renal failure

Calculating Water Deficit

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

• Total body water = Weight (kg) × 0.6 (for men) or 0.5 (for women)

Rate of Correction

• For chronic hypernatremia (>48 hours): Reduce serum sodium by no more than 8-10 mmol/L/day 1, 2
• For acute hypernatremia (<24 hours): Can correct more rapidly, but still monitor closely
• Critical point: Overly rapid correction can lead to cerebral edema, seizures, and neurological injury

Monitoring During Treatment

• Check serum sodium every 2-4 hours initially, then every 4-6 hours once stabilized
• Monitor neurological status closely
• Adjust fluid rate based on sodium measurements
• Track fluid balance meticulously

Special Populations

Critically Ill Patients

• Higher mortality associated with hypernatremia 3
• More aggressive monitoring required
• Consider hemodialysis for acute severe hypernatremia 2

Elderly Patients

• More susceptible to hypernatremia due to impaired thirst mechanism
• May require lower correction rates due to age-related changes in brain adaptation

Prevention Strategies

• Regular assessment of electrolytes in high-risk patients
• Careful fluid prescription in hospitalized patients
• Monitoring of ongoing fluid losses
• Ensuring access to water for patients with altered mental status

Pitfalls to Avoid

1. Overly rapid correction leading to cerebral edema
2. Inadequate assessment of volume status leading to inappropriate fluid choice
3. Failure to identify and treat underlying cause
4. Inadequate monitoring during correction
5. Overlooking ongoing fluid losses that may perpetuate hypernatremia

Remember that hypernatremia reflects an imbalance in water balance, and treatment should focus on both addressing the underlying cause and carefully correcting the sodium abnormality at an appropriate rate to prevent neurological complications.