How to treat hypernatremia?

Treatment of Hypernatremia

The treatment of hypernatremia requires identifying the underlying cause, determining the rate of onset, and correcting the water deficit with hypotonic fluids while avoiding overly rapid correction that could lead to cerebral edema. 1, 2

Initial Assessment

• Confirm true hypernatremia (serum sodium >145 mEq/L)
• Determine if acute (<48 hours) or chronic (>48 hours)
• Assess volume status (hypovolemic, euvolemic, or hypervolemic)
• Calculate water deficit using formula: Water deficit = TBW × [(measured Na⁺/140) - 1]
  • Where TBW (Total Body Water) = 0.6 × weight (kg) for men or 0.5 × weight (kg) for women

Treatment Algorithm Based on Volume Status

1. Hypovolemic Hypernatremia (Most Common)

• First step: Restore intravascular volume with isotonic fluids (0.9% NaCl)
• Second step: Correct free water deficit with hypotonic fluids (0.45% NaCl or 5% dextrose) 1, 2
• Monitor urine output and replace ongoing losses

2. Euvolemic Hypernatremia

• Administer hypotonic fluids (5% dextrose or 0.45% NaCl)
• If diabetes insipidus is present:
  • Central DI: Administer desmopressin (DDAVP) 3
  • Nephrogenic DI: Treat underlying cause, consider thiazide diuretics

3. Hypervolemic Hypernatremia

• Loop diuretics to remove excess sodium and water
• Replace water losses with hypotonic fluids
• Treat underlying condition (e.g., hyperaldosteronism)

Rate of Correction

• Acute hypernatremia (<48 hours): Can correct at faster rate of 1-2 mEq/L/hour
• Chronic hypernatremia (>48 hours): Correct at maximum rate of 8-10 mEq/L/day 2
• Monitor serum sodium every 2-4 hours during initial treatment

Fluid Selection

• 5% dextrose in water (D5W) is preferred for free water replacement
  • Caution in hyperglycemic patients as glucose metabolism leaves free water
• 0.45% saline for patients needing some sodium replacement
• In severe cases with central venous access, sterile water may be administered via central line 4

Special Considerations

• For hypernatremia in diabetic emergencies (DKA/HHS), careful fluid selection is critical as these patients often have significant free water deficits 3
• In patients with impaired renal function, dialysis may be necessary for sodium removal
• Avoid rapid correction in chronic hypernatremia to prevent cerebral edema and neurological damage 5

Monitoring During Treatment

• Serum sodium levels every 2-4 hours initially, then every 4-6 hours
• Monitor for signs of cerebral edema (headache, nausea, altered mental status)
• Track fluid balance (intake/output)
• Monitor other electrolytes (potassium, chloride, bicarbonate)
• Assess hemodynamic parameters (blood pressure, heart rate)

Common Pitfalls to Avoid

• Correcting too rapidly in chronic hypernatremia (risk of cerebral edema)
• Failing to replace ongoing losses
• Not addressing the underlying cause
• Using hypotonic fluids before restoring intravascular volume in hypovolemic patients
• Inadequate monitoring during correction

Remember that hypernatremia has a high mortality rate if not properly managed, especially when severe or when correction is inappropriately performed 5.