How do you treat hypernatremia?

Treatment of Hypernatremia

Immediate Assessment and Correction Rate

For chronic hypernatremia (>48 hours duration), reduce serum sodium by 10-15 mmol/L per 24 hours, never exceeding this rate to prevent cerebral edema, seizures, and permanent neurological injury. 1

• Acute hypernatremia (<24-48 hours) can be corrected more rapidly, up to 1 mmol/L per hour if the patient is severely symptomatic 1
• Slower correction is critical for chronic cases because brain cells synthesize intracellular osmolytes over 48 hours to adapt to hyperosmolar conditions, and rapid correction causes these cells to swell dangerously 1
• Close laboratory monitoring of serum sodium is essential during correction, checking levels every 2-4 hours initially 1, 2

Volume Status-Based Treatment Approach

Hypovolemic Hypernatremia

Administer hypotonic fluids to replace the free water deficit—avoid isotonic saline as initial therapy, especially in patients with nephrogenic diabetes insipidus, as this will worsen hypernatremia. 1

• Hypotonic fluid options include 0.45% NaCl (half-normal saline, 77 mEq/L sodium), 0.18% NaCl (quarter-normal saline, 31 mEq/L sodium), or D5W (5% dextrose in water) 3
• The choice depends on severity: 0.45% NaCl for moderate hypernatremia, more hypotonic solutions like 0.18% NaCl or D5W for severe cases 3
• In patients with severe burns or voluminous diarrhea, match fluid composition to ongoing losses while providing adequate free water 1
• Never use isotonic saline in patients with renal concentrating defects—this exacerbates hypernatremia 1, 3

Euvolemic Hypernatremia

Implement a low-salt diet (<6 g/day) and protein restriction (<1 g/kg/day) for patients with euvolemic hypernatremia. 1

• For nephrogenic diabetes insipidus, ongoing hypotonic fluid administration is required to match excessive free water losses 1
• These patients need continuous free water replacement as they cannot concentrate urine appropriately 1

Hypervolemic Hypernatremia

Focus on achieving negative water balance rather than aggressive fluid administration—discontinue intravenous fluids and implement free water restriction. 1

• In cirrhosis with hypervolemic hypernatremia, the European Association for the Study of the Liver recommends prioritizing negative water balance over fluid resuscitation 1
• This approach prevents worsening fluid overload while allowing gradual sodium correction 1

Special Population Considerations

Heart Failure Patients

Implement sodium and fluid restriction, limiting fluid intake to approximately 2 L/day for most hospitalized patients. 1

• Consider stricter fluid restriction for diuretic-resistant or significantly hypernatremic patients 1
• For persistent severe hypernatremia with cognitive symptoms, vasopressin antagonists (tolvaptan, conivaptan) may be considered for short-term use 1
• After initial correction, fluid restriction of 1.5-2 L/day may be needed with careful monitoring of serum sodium and fluid balance 1

Cirrhosis Patients

Evaluate for hypovolemic versus hypervolemic state first—provide hypotonic fluid resuscitation for hypovolemic hypernatremia, but focus on negative water balance for hypervolemic hypernatremia. 1

• Discontinue IV fluids and implement free water restriction in hypervolemic cases 1
• Close monitoring of serum sodium and fluid status is essential 1

Severe Hypernatremia with Altered Mental Status

Combine IV hypotonic fluids with free water via nasogastric tube, targeting correction of 10-15 mmol/L per 24 hours. 1

• This dual approach allows more controlled correction in critically ill patients 1
• Monitor neurological status closely during correction 1

Critical Pitfalls to Avoid

Correcting chronic hypernatremia too rapidly leads to cerebral edema, seizures, and neurological injury—this is the most dangerous complication. 1

• The risk of "rebound" intracranial pressure elevation exists during correction as brain cells have synthesized intracellular osmolytes 1
• Hypernatremia is associated with hyperchloremia, which may impair renal function—monitor renal function during treatment 1
• The use of prolonged induced hypernatremia to control intracranial pressure in traumatic brain injury is not recommended, as it requires an intact blood-brain barrier and may worsen cerebral contusions 1

Monitoring Protocol

Assess body weight, estimate body composition, measure blood electrolytes, calculate fluid and electrolyte balance, and check hematocrit and blood urea nitrogen to assess hydration status. 1

• Regular monitoring of serum sodium, potassium, chloride, and bicarbonate levels is essential during treatment 1
• Assess renal function and urine osmolality throughout the correction process 1
• For severe cases, check serum sodium every 2-4 hours initially, then adjust frequency based on response 2, 4