From the Guidelines
Hypotonic fluids, specifically 5% dextrose in water (D5W), are the primary treatment for hypernatremia, as they provide free water replacement without adding to the renal osmotic load. For patients with hypernatremia, the goal is to correct the sodium imbalance while preventing cerebral edema. According to the international expert consensus statement on the diagnosis and management of congenital nephrogenic diabetes insipidus (arginine vasopressin resistance) 1, salt-containing solutions, such as NaCl 0.9% solutions, should be avoided due to their large renal osmotic load.
Key Considerations
- The choice of fluid depends on the patient's volume status, with isotonic fluids like 0.9% normal saline used initially for hypovolemic patients to restore volume before switching to hypotonic solutions 1.
- The rate of sodium correction should be gradual, typically not exceeding 8-10 mEq/L per 24 hours (or 0.5 mEq/L/hour) to prevent cerebral edema, especially in chronic hypernatremia.
- Oral free water intake is preferred when possible and safe, and the underlying cause of hypernatremia must be addressed simultaneously, whether it's excessive water loss, inadequate water intake, or diabetes insipidus.
- Regular monitoring of serum sodium levels during treatment is essential to ensure appropriate correction rates and prevent overcorrection.
Treatment Approach
- For most patients with hypernatremia, 5% dextrose in water (D5W) is a suitable option, as it becomes free water once the dextrose is metabolized, making it effective for free water replacement 1.
- In hospitalized patients, close observation of clinical status, including neurological condition, fluid balance, weight, and electrolytes, is recommended, with consideration of placing a urinary catheter to ensure proper monitoring of diuresis 1.
From the Research
Treatment of Hypernatremia
- The treatment of hypernatremia involves replacing the loss of free water by hypotonic infusions 2.
- Hypotonic saline solution or dextrose in water can be used to correct hypernatremia, with the calculation of fluid volume needed based on various formulae 3.
- The cornerstone of treatment is administration of free water to correct the relative water deficit 4.
- In cases of diabetes insipidus, Desmopressin (Minirin) can be used to treat hypernatremia 2.
- For acute hypernatremia (< 24 hours), hemodialysis is an effective option to rapidly normalize the serum sodium levels 2.
Considerations for Treatment
- Rapid changes in serum sodium concentration can have deleterious consequences, such as osmotic demyelination syndrome, and should be avoided 2, 3.
- Preexisting hypernatremia (>48h) should not be reduced by more than 8-10 mmol/l/day 2.
- Close laboratory controls are important to monitor the correction of serum sodium levels 2.
- The speed of correction is important, and too rapid correction of chronic hypernatremia can result in brain edema 3.