How is hypernatremia treated?

Treatment of Hypernatremia

The cornerstone of hypernatremia treatment is administering hypotonic fluids to replace free water deficit while correcting the sodium at a controlled rate of 10-15 mmol/L per 24 hours to prevent cerebral edema. 1

Initial Assessment

Before initiating treatment, evaluate the following parameters to guide therapy 2, 1:

• Volume status (hypovolemic, euvolemic, or hypervolemic) through clinical examination and vital signs 1
• Neurological symptoms including confusion, altered mental status, or seizures 2, 1
• Blood electrolyte concentrations and acid-base status 2
• Fluid balance by measuring urine output, urine specific gravity or osmolarity, and urine electrolyte concentrations 2
• Hematocrit and blood urea nitrogen to assess hydration status 2
• Body weight and estimation of body composition to determine fluid deficits 1

Treatment Strategy Based on Volume Status

Hypovolemic Hypernatremia

• Administer hypotonic fluids to replace free water deficit 1
• Avoid isotonic saline as initial therapy, especially in patients with nephrogenic diabetes insipidus, as this will worsen hypernatremia 1
• For patients with severe burns or voluminous diarrhea, match fluid composition to losses while providing adequate free water 1

Euvolemic Hypernatremia

• Implement low salt diet (<6 g/day) and protein restriction (<1 g/kg/day) 1
• Provide hypotonic fluid replacement to correct the free water deficit 3
• For nephrogenic diabetes insipidus, ongoing hypotonic fluid administration is required to match excessive free water losses 1

Hypervolemic Hypernatremia

• In cirrhosis patients, discontinue intravenous fluid therapy and implement free water restriction 1
• Focus on attaining negative water balance rather than aggressive fluid administration 1
• In heart failure patients, implement sodium and fluid restriction, limiting fluid intake to around 2 L/day 1
• Consider vasopressin antagonists (tolvaptan, conivaptan) for short-term use in heart failure patients with persistent severe hypernatremia and cognitive symptoms 1

Rate of Correction: Critical Safety Parameter

The rate of correction must be adjusted based on chronicity to avoid devastating neurological complications:

Chronic Hypernatremia (>48 hours)

• Reduce sodium by 10-15 mmol/L per 24 hours (approximately 0.4 mmol/L/hour) 2, 1, 4, 5
• Never exceed 8-10 mmol/L per day in chronic cases 4
• Slower correction is critical because brain cells synthesize intracellular osmolytes over 48 hours to adapt to hyperosmolar conditions 1
• Rapid correction causes cerebral edema, seizures, and permanent neurological injury 2, 1

Acute Hypernatremia (<24-48 hours)

• Can be corrected more rapidly, up to 1 mmol/L/hour if severely symptomatic 1
• Rapid correction improves prognosis by preventing effects of cellular dehydration 5
• Hemodialysis is an effective option to rapidly normalize serum sodium levels in acute cases 4

Specific Treatment Modalities

Severe Symptomatic Hypernatremia

For patients with severe hypernatremia and altered mental status, combine IV hypotonic fluids with free water via nasogastric tube, targeting correction rate of 10-15 mmol/L per 24 hours 1

Symptomatic Hypovolemia

In cases of symptomatic hypovolemia, plasma volume should be replaced first before addressing the hypernatremia 2

Special Populations

Very low birth weight infants: Hypernatremia is often iatrogenic, resulting from incorrect replacement of transepidermal water loss, inadequate water intake, or excessive sodium intake 2

Traumatic brain injury: The use of prolonged induced hypernatremia to control intracranial pressure is not recommended, as it requires an intact blood-brain barrier and may worsen cerebral contusions 1

Monitoring During Treatment

Implement close laboratory monitoring to prevent complications 4, 6:

• Daily monitoring of serum sodium, potassium, chloride, and bicarbonate during initial treatment 1
• Frequent serum electrolyte checks to avoid overly rapid correction 3
• Assess renal function and urine osmolality regularly 1
• Monitor for hyperchloremia, which may impair renal function 1
• Adjust monitoring intervals based on clinical status and stability 2

Critical Pitfalls to Avoid

• Never use isotonic saline in patients with renal concentrating defects or nephrogenic diabetes insipidus, as this exacerbates hypernatremia 1
• Avoid rapid correction of chronic hypernatremia, which leads to cerebral edema and osmotic demyelination syndrome 2, 1, 3
• When starting renal replacement therapy in patients with chronic hypernatremia, consider the risk of rapid sodium drop 4
• Do not delay treatment while pursuing a definitive diagnosis of the underlying cause 3