Management of Hypernatremia
The management of hypernatremia should focus on identifying the underlying cause, determining the patient's volume status, and providing appropriate fluid replacement to correct sodium levels at a safe rate.
Assessment and Classification
- Hypernatremia is defined as a serum sodium concentration greater than 145 mmol/L 1, 2
- Classify hypernatremia based on volume status as hypovolemic, euvolemic, or hypervolemic to guide treatment 3, 4
- Determine if hypernatremia is acute (<48 hours) or chronic (>48 hours) as this affects the rate of correction 4, 5
- Assess for neurological symptoms, vital signs, body weight, electrolytes, and acid-base status 3
Treatment Principles
- For hypovolemic hypernatremia, administer hypotonic fluids to replace free water deficit and avoid isotonic saline as initial therapy 3
- For euvolemic hypernatremia, focus on free water replacement 1, 4
- For hypervolemic hypernatremia, focus on attaining negative water balance and treating the underlying cause 3
- The rate of correction should not exceed 10-15 mmol/L/24 hours for chronic hypernatremia to avoid complications 3, 5
- For acute hypernatremia (<24 hours), more rapid correction may be appropriate 5
Specific Treatment Approaches
Hypovolemic Hypernatremia
- Replace both the sodium and water deficit with hypotonic solutions 3, 1
- Calculate free water deficit to guide initial fluid replacement therapy 2
- Monitor plasma sodium levels frequently to adjust the rate of fluid replacement 2
Euvolemic Hypernatremia
- Often seen in diabetes insipidus (central or nephrogenic) 4
- For central diabetes insipidus, consider desmopressin (Minirin) 5
- For nephrogenic diabetes insipidus, treat underlying causes (e.g., lithium toxicity, hypokalemia) 4
- Low salt diet (<6 g/day) and protein restriction (<1 g/kg/day) may be beneficial 6
Hypervolemic Hypernatremia
- Treat the underlying cause (e.g., heart failure, cirrhosis) 3, 1
- In heart failure patients with hypernatremia, sodium and fluid restriction is recommended, limiting fluid intake to around 2 L/day 3
- For severe cases, consider diuretics to remove excess sodium 2
Special Considerations
- In patients with heart failure who have persistent severe hypernatremia with cognitive symptoms despite water restriction and maximization of guideline-directed medical therapy, vasopressin antagonists (tolvaptan, conivaptan) may be considered for short-term use 6
- For patients with chronic kidney disease, more frequent monitoring is recommended 6
- In critically ill ICU patients, routine assessment of free water requirements and judicious electrolyte and free water replacement is essential 2
Monitoring and Follow-up
- Monitor serum sodium, potassium, chloride, and bicarbonate levels regularly during treatment 6
- Assess renal function and urine osmolality 6, 3
- In children with hypernatremia, approximately 10-15% with serum sodium ≥160 mEq/L may have permanent neurological deficits if not managed properly 7