What are the treatment options for hyponatremia?

Treatment Options for Hyponatremia

The treatment of hyponatremia should be based on symptom severity, volume status, and underlying cause, with careful attention to correction rates to prevent osmotic demyelination syndrome. 1

Initial Assessment and Classification

• Hyponatremia evaluation should include serum and urine osmolarity, urine electrolytes, uric acid, and assessment of extracellular fluid volume status to determine the underlying cause 2, 1
• Categorize patients according to volume status: hypovolemic, euvolemic, or hypervolemic hyponatremia 1, 3
• A serum sodium value less than 131 mmol/L should prompt a comprehensive workup 2

Treatment Based on Symptom Severity

Severe Symptomatic Hyponatremia (seizures, coma, altered mental status)

• Administer 3% hypertonic saline with an initial goal to correct 6 mmol/L over 6 hours or until severe symptoms resolve 2, 1, 4
• Total correction should not exceed 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome 2, 1, 4
• After initial 6 mmol/L correction, limit to only 2 mmol/L in the following 18 hours 4
• Consider ICU admission for close monitoring during treatment 1
• Discontinue 3% saline when severe symptoms resolve and transition to protocols for mild symptoms or asymptomatic hyponatremia 4

Mild to Moderate Symptomatic Hyponatremia

• For chronic hyponatremia, avoid rapid correction exceeding 1 mmol/L/hour 2, 1
• Patients with advanced liver disease, alcoholism, malnutrition, or prior encephalopathy require more cautious correction (4-6 mmol/L per day) 1

Treatment Based on Volume Status

Hypovolemic Hyponatremia

• Discontinue diuretics and administer isotonic saline (0.9% NaCl) for volume repletion 1, 5
• Address the underlying cause (e.g., gastrointestinal losses, renal losses) 1, 6

Euvolemic Hyponatremia (SIADH)

• Fluid restriction to 1L/day is the cornerstone of treatment for mild/asymptomatic cases 1, 7
• Consider pharmacological options for resistant cases:
  • Tolvaptan (vasopressin receptor antagonist) for clinically significant hyponatremia resistant to fluid restriction, starting at 15 mg once daily 1, 8
  • Tolvaptan showed significant improvement in serum sodium levels compared to placebo in clinical trials 8
  • Other options include demeclocycline, lithium, or urea 1, 3

Hypervolemic Hyponatremia (heart failure, cirrhosis)

• Implement fluid restriction to 1000-1500 mL/day for moderate hyponatremia (120-125 mmol/L) 1, 5
• For severe hyponatremia (<120 mmol/L), consider more severe fluid restriction plus albumin infusion 1
• Avoid hypertonic saline unless life-threatening symptoms are present, as it may worsen edema and ascites 1

Special Considerations

Cerebral Salt Wasting (CSW)

• Treatment focuses on volume and sodium replacement, not fluid restriction 2, 1
• For severe symptoms, administer 3% hypertonic saline and fludrocortisone 2, 1
• Subarachnoid hemorrhage patients receive treatment even for sodium levels of 131-135 mmol/L 2, 4

Patients with Liver Disease

• Require more cautious correction (4-6 mmol/L per day) due to higher risk of osmotic demyelination syndrome 1
• Consider albumin infusion alongside fluid restriction in cirrhotic patients 1

Monitoring During Treatment

• For severe symptoms: monitor serum sodium every 2 hours during initial correction 1
• After resolution of severe symptoms, monitor every 4 hours 4
• Calculate sodium deficit using formula: Desired increase in Na (mEq/L) × (0.5 × ideal body weight in kg) 1

Common Pitfalls to Avoid

• Overly rapid correction of chronic hyponatremia leading to osmotic demyelination syndrome 2, 1, 3
• Using fluid restriction in cerebral salt wasting, which can worsen outcomes 2, 1
• Failing to recognize and treat the underlying cause 1, 6
• Using hypertonic saline in hypervolemic hyponatremia without life-threatening symptoms 1
• Inadequate monitoring during active correction 1

Pharmacological Considerations

• Tolvaptan may cause gastrointestinal bleeding in patients with cirrhosis (10% vs 2% with placebo) 8
• Common adverse effects of tolvaptan include thirst (14%), dry mouth (13%), and polyuria (11%) 8
• Hypernatremia occurred in 1.7% of patients receiving tolvaptan vs. 0.8% receiving placebo 8
• Avoid concomitant use of tolvaptan with strong CYP3A inhibitors 8