What is the treatment for hyponatremia?

Treatment of Hyponatremia

The treatment of hyponatremia should be based on the underlying cause, symptom severity, and volume status, with correction rates not exceeding 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome. 1

Initial Assessment and Classification

• Hyponatremia should be further investigated and treated when serum sodium is less than 131 mmol/L 2
• Classify patients according to volume status: hypovolemic, euvolemic, or hypervolemic 1, 3
• Initial workup should include serum and urine osmolarity, urine electrolytes, uric acid, and assessment of extracellular fluid volume status 1

Treatment Based on Symptom Severity

Severe Symptomatic Hyponatremia (seizures, coma)

• Administer 3% hypertonic saline with an initial goal to correct 6 mmol/L over 6 hours or until severe symptoms resolve 1
• Do not exceed total correction of 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome 1, 4
• Consider ICU admission for close monitoring during treatment 1

Mild to Moderate Symptomatic Hyponatremia

• Treatment should be based on severity of symptoms 2
• Correction should not exceed 8 mmol/L/day 2, 1
• For patients with liver disease, alcoholism, or malnutrition, use more conservative correction rates (4-6 mmol/L per day) due to higher risk of osmotic demyelination 1

Treatment Based on Volume Status

Hypovolemic Hyponatremia

• Discontinue diuretics if applicable 1
• Administer isotonic saline (0.9% NaCl) for volume repletion 1, 3
• For severe dehydration with neurological symptoms, consider hypertonic saline with careful monitoring 1

Euvolemic Hyponatremia (SIADH)

• Fluid restriction to 1 L/day is the cornerstone of treatment 1, 4
• Consider oral sodium chloride supplementation if no response to fluid restriction 1
• For persistent cases, options include:
  • Urea 1, 4
  • Diuretics 2
  • Lithium 2
  • Demeclocycline 2
  • Tolvaptan (vasopressin receptor antagonist) for clinically significant hyponatremia resistant to fluid restriction 1, 5

Hypervolemic Hyponatremia (heart failure, cirrhosis)

• Implement fluid restriction to 1-1.5 L/day for serum sodium <125 mmol/L 1
• Consider albumin infusion for patients with cirrhosis 1
• Avoid hypertonic saline unless life-threatening symptoms are present, as it may worsen edema and ascites 1
• Loop diuretics may be useful in managing edematous hyponatremic states 6

Special Considerations for Neurosurgical Patients

• Cerebral salt wasting (CSW) should be treated with replacement of serum sodium and intravenous fluids 2
• Fludrocortisone may be considered in the treatment of hyponatremia in subarachnoid hemorrhage patients at risk of vasospasm 2
• Hydrocortisone may be used to prevent natriuresis in subarachnoid hemorrhage patients 2
• Hyponatremia in subarachnoid hemorrhage patients at risk of vasospasm should not be treated with fluid restriction 2

Monitoring and Safety Considerations

• For severe symptoms: monitor serum sodium every 2 hours during initial correction 1
• Calculate sodium deficit using formula: Desired increase in Na (mEq/L) × (0.5 × ideal body weight in kg) 1
• If overcorrection occurs, consider relowering with electrolyte-free water or desmopressin 1, 7
• Watch for signs of osmotic demyelination syndrome (dysarthria, dysphagia, oculomotor dysfunction, quadriparesis) typically occurring 2-7 days after rapid correction 1, 4

Common Pitfalls to Avoid

• Overly rapid correction of chronic hyponatremia leading to osmotic demyelination syndrome 1, 8
• Inadequate monitoring during active correction 1
• Using fluid restriction in cerebral salt wasting (can worsen outcomes) 1
• Failing to recognize and treat the underlying cause 1
• Using hypertonic saline in hypervolemic hyponatremia without life-threatening symptoms 1