What is the treatment for hypernatremia?

Treatment of Hypernatremia

The treatment of hypernatremia should focus on gradual correction of the sodium imbalance with hypotonic fluids while addressing the underlying cause, with a maximum correction rate not exceeding 8-10 mmol/L per day for chronic hypernatremia to prevent neurological complications. 1, 2

Diagnosis and Assessment

Before initiating treatment, proper assessment is crucial:

• Hypernatremia is defined as serum sodium concentration >145 mEq/L
• Assess volume status (hypovolemic, euvolemic, or hypervolemic)
• Determine acuity (acute: <48 hours vs chronic: >48 hours)
• Evaluate for symptoms (thirst, confusion, lethargy, seizures, coma)
• Check urine osmolality to help determine etiology

Treatment Algorithm

Step 1: Calculate Water Deficit

Calculate the free water deficit using the formula:

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

Step 2: Choose Appropriate Fluid Based on Volume Status

For Hypovolemic Hypernatremia:

• Initial fluid resuscitation with isotonic saline (0.9% NaCl) to restore hemodynamic stability 2
• Once hemodynamically stable, switch to hypotonic fluids (0.45% NaCl or 5% dextrose in water)

For Euvolemic Hypernatremia:

• 5% dextrose in water (D5W) or 0.45% NaCl 2, 1
• For diabetes insipidus: administer desmopressin (DDAVP) 1

For Hypervolemic Hypernatremia:

• Loop diuretics to promote free water excretion
• 5% dextrose in water (D5W) to replace free water
• Consider dialysis for severe cases with renal failure 3

Step 3: Determine Rate of Correction

• For acute hypernatremia (<48 hours): Can correct more rapidly, but still monitor closely 1
• For chronic hypernatremia (>48 hours): Correct at maximum rate of 8-10 mmol/L/day 1
• Monitor serum sodium every 2-4 hours initially during correction

Special Considerations

Continuous Renal Replacement Therapy (CRRT)

For patients requiring CRRT, hypernatremia can be safely corrected by manipulating the dialysate/replacement fluid sodium concentration 3:

• Add calculated amounts of sterile water to dialysate/replacement fluid to achieve desired sodium concentration
• Adjust in a stepwise manner to prevent too rapid correction

Pediatric Patients

• Children are at higher risk for developing hypernatremia due to higher body water percentage
• More aggressive monitoring may be required
• Same principles of correction rate apply

Common Pitfalls to Avoid

1. Correcting too rapidly: Can lead to cerebral edema, seizures, and permanent neurological damage
2. Inadequate monitoring: Serum sodium should be checked frequently during correction
3. Failure to identify and treat underlying cause: Address conditions like diabetes insipidus, excessive water loss, or salt intoxication
4. Overcorrection: Can be as dangerous as the initial hypernatremia

Underlying Causes to Address

• Limited access to water
• Diabetes insipidus (central or nephrogenic)
• Excessive sodium intake
• Osmotic diuresis
• Heat stroke
• Severe diarrhea or vomiting
• Excessive diuretic use
• Renal disease

Remember that hypernatremia rarely develops in patients with adequate access to water and normal thirst mechanisms 4. Therefore, ensuring adequate water intake in at-risk patients (elderly, critically ill, infants) is crucial for prevention.