Correction of Hypernatremia
The correction of hypernatremia should be performed at a rate not exceeding 0.5 mmol/L per hour, with a maximum of 8-12 mmol/L per 24 hours, to prevent neurological complications. 1
Assessment and Classification
- Hypernatremia occurs when the water content of body fluids is deficient compared to sodium content, resulting in serum sodium >145 mmol/L 2
- Determine the cause of hypernatremia by assessing volume status and calculating water deficit 3
- Evaluate for sodium gain and/or free water loss through clinical assessment and urine electrolyte analysis 4
Treatment Approach Based on Onset
Acute Hypernatremia (developed within 48 hours)
- Can be corrected more rapidly at a rate of up to 1 mmol/L/hour 5
- Still should not exceed 12 mmol/L in 24 hours to minimize risk of cerebral edema 1
Chronic Hypernatremia (developed over >48 hours)
- Requires slower correction at a rate not exceeding 0.5 mmol/L/hour 1
- Maximum correction of 8 mmol/L in 24 hours is recommended to prevent neurological complications 1
Treatment Based on Volume Status
Hypovolemic Hypernatremia
- Initial treatment with isotonic saline (0.9% NaCl) to restore intravascular volume 3
- Once hemodynamically stable, switch to hypotonic fluids (0.45% NaCl or 5% dextrose) to correct free water deficit 3
Euvolemic Hypernatremia
- Administer hypotonic fluids (0.45% NaCl or 5% dextrose) to replace free water deficit 3
- Consider treating underlying causes such as diabetes insipidus if present 3
Hypervolemic Hypernatremia
- Combination of loop diuretics to promote sodium excretion and hypotonic fluids to replace free water deficit 4
- Monitor fluid balance and electrolytes closely 4
Calculating Water Deficit
- Water deficit (L) = [(Current Na⁺ / Desired Na⁺) - 1] × Total body water 3
- Total body water is approximately 60% of body weight in men and 50% in women 3
- Adjust replacement rate to achieve target correction rate 4
Monitoring During Correction
- Check serum sodium levels every 2-4 hours initially, then every 4-6 hours once stabilized 1
- Monitor neurological status for signs of cerebral edema (headache, altered mental status, seizures) 2
- Adjust fluid administration rate based on serial sodium measurements 4
Special Considerations
- Critically ill patients may tolerate more rapid correction rates without increased risk of adverse outcomes, but caution is still advised 1
- Patients with impaired thirst mechanisms (elderly, sedated, or neurologically impaired) require closer monitoring 4
- In patients with diabetes insipidus, address the underlying hormonal deficiency alongside free water replacement 3
Common Pitfalls to Avoid
- Correcting hypernatremia too rapidly can lead to cerebral edema, seizures, and permanent neurological damage 2
- Failing to identify and treat the underlying cause of hypernatremia 4
- Inadequate monitoring of serum sodium levels during correction 1
- Overcorrection of hypernatremia leading to iatrogenic hyponatremia 3