What is the treatment for hypernatremia?

Treatment of Hypernatremia

The treatment of hypernatremia should focus on correcting the free water deficit at an appropriate rate based on the acuity of onset, with chronic hypernatremia (>48 hours) requiring slower correction at a rate not exceeding 8-10 mmol/L/day to prevent cerebral edema. 1, 2

Initial Assessment and Classification

• Determine if hypernatremia is acute (<48 hours) or chronic (>48 hours), as this affects the rate of correction 1
• Assess volume status (hypovolemic, euvolemic, or hypervolemic) to guide appropriate fluid therapy 2
• Check glucose levels to calculate corrected sodium concentration and rule out hyperglycemia as a contributing factor 3, 2
• Evaluate urine osmolality and sodium concentration to determine the underlying cause 2

Treatment Based on Volume Status

Hypovolemic Hypernatremia

• Replace both water and sodium deficits with isotonic fluids (0.9% saline) initially to restore hemodynamic stability 4, 2
• Once hemodynamically stable, switch to hypotonic fluids (0.45% saline or 5% dextrose in water) to correct the free water deficit 1, 2

Euvolemic Hypernatremia

• Administer hypotonic fluids (5% dextrose in water or 0.45% saline) to replace free water deficit 1, 5
• For diabetes insipidus, administer desmopressin (DDAVP) alongside fluid replacement 1, 2

Hypervolemic Hypernatremia

• Rare condition usually caused by excessive sodium intake or administration 5
• Combine loop diuretics with hypotonic fluid replacement to remove excess sodium while correcting free water deficit 5
• Consider hemodialysis for severe cases, especially with renal failure 1

Calculation of Water Deficit and Correction Rate

• Calculate water deficit using formula: Water deficit = Total body water × [(Current Na⁺/140) - 1] 2
• Total body water is approximately 60% of body weight in young men, 50% in young women and elderly men, and 45% in elderly women 2
• For chronic hypernatremia (>48 hours), correct at a rate not exceeding 8-10 mmol/L/day 1, 2
• For acute hypernatremia (<24 hours), correction can be more rapid but still carefully monitored 1

Special Considerations

• In severe hypernatremia (>170 mmol/L), initiate treatment immediately with careful monitoring 5
• Replace the calculated water deficit over 48-72 hours for chronic hypernatremia 5
• Monitor serum sodium levels every 2-4 hours during initial treatment 2
• Adjust fluid administration rate based on serum sodium response 2
• For diabetes insipidus, address the underlying cause while providing desmopressin and fluid replacement 1, 2

Common Pitfalls to Avoid

• Too rapid correction of chronic hypernatremia can lead to cerebral edema and neurological deterioration 1, 5
• Inadequate monitoring of serum sodium levels during correction 2
• Failure to identify and address the underlying cause 4, 2
• Overestimation of free water deficit in patients with hyperglycemia (must use corrected sodium) 3, 2
• Using isotonic fluids alone for treatment of pure free water deficit 1, 2

Case Example

• A case report documented successful treatment of extreme hypernatremia (corrected sodium of 202 mmol/L) by slow correction at a rate of 0.46 mmol/L/hour over 91 hours, demonstrating the safety of careful correction 3