What is the treatment for hyponatremia?

Treatment of Hyponatremia

The treatment of hyponatremia should be guided by symptom severity, volume status, and the rate of sodium decline, with correction rates not exceeding 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome. 1

Initial Assessment and Classification

• Hyponatremia is defined as serum sodium <135 mmol/L, with clinical significance typically at levels <131 mmol/L 1
• Classify patients based on volume status: hypovolemic, euvolemic, or hypervolemic hyponatremia 1
• Assess symptom severity: mild/asymptomatic, moderate, or severe (seizures, coma) 1
• Determine acuity: acute (<48 hours) or chronic (>48 hours) 1
• Initial workup should include serum and urine osmolality, urine electrolytes, and assessment of extracellular fluid volume status 1

Treatment Based on Symptom Severity

Severe Symptomatic Hyponatremia (seizures, coma)

• Administer 3% hypertonic saline immediately with an initial goal to correct 6 mmol/L over 6 hours or until severe symptoms resolve 1
• Can be given as 100 mL boluses over 10 minutes, repeated up to three times at 10-minute intervals until symptoms improve 1
• Total correction should not exceed 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome 1
• Consider ICU admission for close monitoring during treatment 1

Moderate Symptomatic Hyponatremia

• Implement treatment based on underlying cause and volume status 1
• Correction rate should not exceed 8 mmol/L in 24 hours 1
• Monitor serum sodium every 4-6 hours during correction 1

Mild/Asymptomatic Hyponatremia

• Treatment should address the underlying cause 2
• Fluid restriction to 1-1.5 L/day for euvolemic or hypervolemic hyponatremia 1
• Discontinue medications that may contribute to hyponatremia 1

Treatment Based on Volume Status

Hypovolemic Hyponatremia

• Discontinue diuretics and administer isotonic saline (0.9% NaCl) for volume repletion 1
• Once euvolemia is achieved, a 24-hour urine collection for sodium can help confirm the diagnosis 1

Euvolemic Hyponatremia (SIADH)

• Fluid restriction to 1 L/day is the cornerstone of treatment 1
• Consider pharmacological options for resistant cases:
  • Urea (30-60 g/day) 1
  • Vasopressin receptor antagonists (tolvaptan, conivaptan) 3
  • Demeclocycline or lithium (less commonly used due to side effects) 1

Hypervolemic Hyponatremia (heart failure, cirrhosis)

• 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

Special Considerations

Neurosurgical Patients

• Distinguish between SIADH and cerebral salt wasting (CSW) as treatment approaches differ significantly 4, 1
• For CSW, treatment focuses on volume and sodium replacement, not fluid restriction 1
• Fludrocortisone may be considered in subarachnoid hemorrhage patients at risk of vasospasm 1
• Avoid fluid restriction in subarachnoid hemorrhage patients at risk of vasospasm 1

Patients with Liver Disease or Malnutrition

• Use more cautious correction rates (4-6 mmol/L per day) due to higher risk of osmotic demyelination syndrome 1
• For cirrhotic patients with hypervolemic hyponatremia, fluid restriction and albumin infusion may be necessary 1

Medication Considerations

• Tolvaptan has been shown to increase serum sodium in patients with euvolemic or hypervolemic hyponatremia 3
• In clinical trials, tolvaptan caused a statistically greater increase in serum sodium compared to placebo 3
• Caution is advised when using tolvaptan in patients with cirrhosis due to higher risk of gastrointestinal bleeding (10% vs 2% with placebo) 3

Correction Rate Guidelines

• For most patients: do not exceed 8 mmol/L in 24 hours 1
• For high-risk patients (liver disease, alcoholism, malnutrition): limit to 4-6 mmol/L per day 1
• If overcorrection occurs, consider relowering with electrolyte-free water or desmopressin 1

Monitoring During Treatment

• For severe symptoms: monitor serum sodium every 2 hours during initial correction 1
• For moderate symptoms: monitor every 4-6 hours 1
• Watch for signs of osmotic demyelination syndrome (dysarthria, dysphagia, oculomotor dysfunction, quadriparesis) typically occurring 2-7 days after rapid correction 1

Common Pitfalls to Avoid

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