What is the treatment for hypernatraemia?

Treatment of Hypernatremia

The treatment of hypernatremia should be based on the underlying etiology, with correction of serum sodium at a rate of 10-15 mmol/L/24 hours to prevent neurological complications. 1

Diagnosis and Classification

Hypernatremia is defined as serum sodium concentration >145 mmol/L and can be classified based on:

• Volume status:

  • Hypervolemic (excess sodium)
  • Hypovolemic (water loss exceeds sodium loss)
  • Euvolemic (pure water deficit) 2, 3

• Duration:

  • Acute (<48 hours)
  • Chronic (>48 hours) 2

• Severity:

  • Mild
  • Moderate
  • Severe 2

Initial Assessment

• Evaluate volume status (physical examination, vital signs) 1
• Measure serum electrolytes, acid-base status 1
• Assess fluid balance (urine output, urine specific gravity/osmolarity, urine electrolytes) 1
• Check hematocrit and blood urea nitrogen 1

Treatment Approach

1. Identify and Treat Underlying Cause

Common causes include:

• Inadequate water intake 1
• Excessive water loss (renal or extrarenal) 2
• Excessive sodium intake (iatrogenic) 1
• Diabetes insipidus (central or nephrogenic) 2

2. Determine Rate of Correction

• For acute hypernatremia (<48 hours): More rapid correction is acceptable
• For chronic hypernatremia (>48 hours): Slow correction at rate of 10-15 mmol/L/24 hours 1, 4

3. Calculate Water Deficit

Water deficit can be calculated using the formula:

• Water deficit = Total body water × [(Current Na⁺/140) - 1] 4
• Total body water is approximately 60% of body weight in men and 50% in women 4

4. Choose Appropriate Fluid Replacement

• Hypervolemic hypernatremia:

  • Loop diuretics to remove excess sodium 2
  • Hypotonic fluids (5% dextrose) 3
  • Consider hemodialysis in severe cases 5

• Hypovolemic hypernatremia:

  • Initial volume resuscitation with isotonic fluids if hemodynamically unstable 3
  • Followed by hypotonic fluids (0.45% saline or 5% dextrose) 3, 4

• Euvolemic hypernatremia:

  • Hypotonic fluids (5% dextrose or 0.45% saline) 3
  • For diabetes insipidus: Desmopressin (central DI) or treat underlying cause (nephrogenic DI) 5

5. Monitor Response to Treatment

• Regular monitoring of serum sodium (every 2-4 hours initially) 1
• Adjust fluid administration rate based on sodium changes 4
• Monitor for signs of cerebral edema (headache, altered mental status, seizures) 1

Special Considerations

Nephrogenic Diabetes Insipidus (NDI)

• Low salt (<6 g/day) and protein diet (<1 g/kg/day) 1
• Consider thiazide diuretics 1
• Prostaglandin synthesis inhibitors may be beneficial but should be discontinued once continence is achieved 1

Heart Failure with Hypernatremia

• In patients with volume overload and persistent severe hypernatremia:
  • Water restriction and maximization of guideline-directed medical therapy
  • Vasopressin antagonists (vaptans) may be considered short-term 1

Cirrhosis with Hypernatremia

• Avoid rapid correction to prevent central pontine myelinolysis 1
• Hypertonic sodium chloride (3%) should be reserved for severely symptomatic acute hypernatremia, especially if transplant is imminent 1

Complications of Treatment

• Too rapid correction: Cerebral edema, seizures, neurological injury 1
• Too slow correction: Continued cellular dehydration and neurological symptoms 2
• Osmotic demyelination syndrome: Can occur with rapid correction of chronic hypernatremia 5

Prevention

• Regular monitoring of serum electrolytes in high-risk patients 1
• Careful administration of hypertonic solutions 2
• Appropriate fluid replacement in patients unable to maintain adequate oral intake 3

Remember that the treatment of hypernatremia requires careful attention to the rate of correction to prevent neurological complications while addressing the underlying cause.