What is the treatment for hypernatremia?

Treatment of Hypernatremia

For hypernatremia, administer hypotonic fluids to replace the free water deficit, avoiding isotonic saline as initial therapy, with a correction rate of 10-15 mmol/L per 24 hours to prevent cerebral edema. 1

Initial Assessment and Volume Status Determination

The treatment approach depends critically on the patient's volume status:

• Hypovolemic hypernatremia results from combined water and sodium losses (but proportionally more water loss), presenting with signs of dehydration including hypotension, tachycardia, dry mucous membranes, and decreased skin turgor 2, 3

• Euvolemic hypernatremia typically indicates diabetes insipidus (central or nephrogenic) or insensible water losses, with patients appearing relatively normal in volume status 3

• Hypervolemic hypernatremia occurs from excessive sodium intake (hypertonic saline, sodium bicarbonate infusions) or primary hyperaldosteronism, with patients showing signs of volume overload 3

Treatment Algorithm Based on Volume Status

Hypovolemic Hypernatremia

Replace free water deficit with hypotonic fluids (0.45% saline or D5W), never isotonic saline as initial therapy. 1 This is particularly critical in patients with nephrogenic diabetes insipidus, where isotonic fluids will worsen hypernatremia 1

• Calculate the free water deficit using: Water deficit (L) = 0.6 × body weight (kg) × [(current Na/140) - 1] 2
• Replace half the calculated deficit over the first 24 hours, then the remainder over the next 24-48 hours 2

Euvolemic Hypernatremia

• For diabetes insipidus, administer desmopressin (Minirin) in addition to free water replacement 4
• Provide hypotonic fluids (D5W or 0.45% saline) to replace ongoing losses 2, 3
• For patients with cirrhosis and hypernatremia, evaluate carefully as this may indicate worsening hemodynamic status requiring hypotonic fluid resuscitation 1

Hypervolemic Hypernatremia

• Focus on achieving negative water balance through diuretics while providing free water replacement 1
• In heart failure patients, implement sodium and fluid restriction, limiting intake to approximately 2 L/day 1
• For diuretic-resistant or significantly hypernatremic heart failure patients, consider stricter fluid restriction 1

Correction Rate Guidelines

The correction rate is absolutely critical to prevent devastating neurological complications:

• For chronic hypernatremia (>48 hours duration): Reduce sodium by no more than 10-15 mmol/L per 24 hours 1, 4
• Maximum safe correction rate: 0.4 mmol/L per hour 3
• Never exceed 8-10 mmol/L reduction in 24 hours for chronic hypernatremia to avoid cerebral edema 4

The slower correction rate for chronic hypernatremia is essential because brain cells adapt by accumulating organic osmolytes over 24-48 hours. Rapid correction causes water to shift into brain cells faster than osmolytes can be expelled, resulting in cerebral edema, seizures, and neurological injury 1

Acute vs. Chronic Hypernatremia

• Acute hypernatremia (<24 hours): Can be corrected more rapidly as brain adaptation has not occurred; hemodialysis is an effective option for rapid normalization 4
• Chronic hypernatremia (>48 hours): Requires slow, controlled correction as described above 3, 4

Specific Treatment Considerations

Dietary Management

• For euvolemic hypernatremia, implement a low salt diet (<6 g/day) and protein restriction (<1 g/kg/day) 1

Pharmacological Options

• Vasopressin antagonists (tolvaptan, conivaptan) may be considered for short-term use in heart failure patients with persistent severe hypernatremia and cognitive symptoms 1

Cirrhosis-Specific Management

• For hypervolemic hypernatremia in cirrhosis, discontinue intravenous fluid therapy and implement free water restriction 1
• Sodium levels of 150 mmol/L in cirrhotic patients are particularly concerning as they may indicate worsening hemodynamic status 5

Monitoring Requirements

• Assess body weight and body composition to determine fluid deficits 1
• Measure blood electrolytes and acid-base status regularly 1
• Check hematocrit and blood urea nitrogen to assess hydration status 1
• Monitor serum sodium, potassium, chloride, and bicarbonate levels during treatment 1
• Assess renal function and urine osmolality throughout the correction process 1

Critical Pitfalls to Avoid

• Never use isotonic saline as initial therapy for hypovolemic hypernatremia, especially in nephrogenic diabetes insipidus patients 1
• Correcting chronic hypernatremia too rapidly leads to cerebral edema, seizures, and potentially irreversible neurological injury 1
• Failing to calculate and monitor correction rates can result in overcorrection 2
• Starting renal replacement therapy without adjusting dialysate in chronic hypernatremia patients can cause dangerous rapid sodium drops 4