How is hypernatremia treated?

Treatment of Hypernatremia

Hypernatremia treatment should be based on the underlying cause, with water replacement as the cornerstone of therapy, administered at a controlled rate of correction not exceeding 10-15 mmol/L per 24 hours to prevent cerebral edema.

Assessment and Classification

First, determine the type of hypernatremia based on volume status:

1. Hypovolemic hypernatremia: Water and sodium loss with greater water than sodium loss
2. Euvolemic hypernatremia: Pure water loss
3. Hypervolemic hypernatremia: Sodium gain exceeding water gain

Initial Management Steps

For Emergency Situations (Severe Symptomatic Hypernatremia)

• Symptoms requiring urgent treatment: Seizures, altered consciousness, coma
• Initial intervention: Administer hypotonic fluids (5% dextrose in water) 1
• Monitoring: Check serum sodium levels frequently (every 2-4 hours initially)

Rate of Correction

• Acute hypernatremia (developed within 48 hours): Can be corrected more rapidly
• Chronic hypernatremia: Correct at a rate of 10-15 mmol/L/day maximum 1
• Warning: Rapid correction can cause cerebral edema, seizures, and neurological injury 1

Fluid Selection and Administration

Hypovolemic Hypernatremia

1. First step: Replace intravascular volume with isotonic fluids if hemodynamically unstable
2. Second step: Switch to hypotonic solutions (5% dextrose) once hemodynamically stable 1
3. Calculation: Determine water deficit using the formula:
   • Water deficit = Total body water × [(Current Na⁺/140) - 1]
   • Total body water ≈ 0.6 × body weight (kg) in adults

Euvolemic Hypernatremia

1. Primary treatment: Hypotonic fluids (5% dextrose in water) 1
2. Route: Oral or enteral if possible; intravenous if necessary
3. Underlying cause management:
   • For diabetes insipidus: Consider desmopressin (DDAVP)
   • For excessive insensible losses: Address fever, hyperventilation

Hypervolemic Hypernatremia

1. Primary approach: Remove excess sodium while replacing water
2. Methods:
   • Loop diuretics to promote sodium excretion
   • Hypotonic fluids to correct free water deficit 1
   • Consider hemodialysis in severe cases with renal failure

Special Considerations

Nephrogenic Diabetes Insipidus (NDI)

• Avoid salt-containing solutions (0.9% NaCl) as they worsen hypernatremia 1
• Recommended fluid: 5% dextrose in water
• Maintenance rate calculation:
  • Children: First 10 kg: 100 ml/kg/24h; 10-20 kg: 50 ml/kg/24h; remaining: 20 ml/kg/24h
  • Adults: 25-30 ml/kg/24h 1

Critically Ill Patients

• Higher risk population: More frequent monitoring required
• Complications: Hypernatremia increases mortality in ICU patients 2
• Management: Careful sodium and water balance with regular electrolyte monitoring

Monitoring During Treatment

• Serum sodium: Check every 2-4 hours initially, then every 4-6 hours
• Urine output: Monitor closely to adjust fluid replacement
• Clinical status: Assess for improvement in neurological symptoms
• Other electrolytes: Monitor potassium, chloride, bicarbonate 1

Common Pitfalls to Avoid

1. Too rapid correction leading to cerebral edema
2. Inadequate monitoring of serum sodium during correction
3. Using isotonic saline in patients with NDI (worsens hypernatremia) 1
4. Failure to address the underlying cause of hypernatremia
5. Overlooking ongoing water losses when calculating replacement needs

Follow-up Care

• Continue monitoring serum sodium until stable in normal range
• Address underlying conditions that led to hypernatremia
• Educate patients/caregivers about adequate fluid intake if appropriate
• Consider regular follow-up for patients with chronic conditions predisposing to hypernatremia

Remember that the correction of hypernatremia must be carefully controlled to prevent neurological complications, with the rate determined by whether the condition developed acutely or chronically.