How to correct hyponatremia?

Management of Hyponatremia

The treatment of hyponatremia should be based on symptom severity, volume status, and onset timing, with a maximum correction rate of 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome. 1

Initial Assessment and Classification

• Classify hyponatremia based on volume status: hypovolemic, euvolemic, or hypervolemic 1
• Determine symptom severity: severe (seizures, coma), moderate (confusion, lethargy), or mild/asymptomatic 1
• Assess onset timing: acute (<48 hours) or chronic (>48 hours) 1
• Initial workup should include serum and urine osmolality, 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
• Can be given as boluses of 100 mL over 10 minutes, repeatable up to three times at 10-minute intervals until symptoms improve 1
• Patients should be in a hospital for initiation and re-initiation of therapy to evaluate therapeutic response and prevent osmotic demyelination 2
• Monitor serum sodium every 2 hours during initial correction 1

Mild to Moderate Symptomatic or Asymptomatic Hyponatremia

• Treatment depends on volume status (see below) 1
• Avoid fluid restriction during the first 24 hours of therapy with tolvaptan 2
• Maximum correction should not exceed 8 mmol/L in 24 hours (4-6 mmol/L for high-risk patients) 1

Treatment Based on Volume Status

Hypovolemic Hyponatremia

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

Euvolemic Hyponatremia (SIADH)

• Fluid restriction to 1L/day for mild/asymptomatic cases 1
• Consider pharmacological options for resistant cases:
  • Urea (effective and safe treatment) 3
  • Tolvaptan (vasopressin receptor antagonist) starting at 15 mg once daily, can increase to 30 mg after 24 hours, maximum 60 mg daily 2
  • Other options: diuretics, lithium, demeclocycline 1

Hypervolemic Hyponatremia (cirrhosis, heart failure)

• Fluid restriction to 1000-1500 mL/day for moderate hyponatremia (Na <125 mmol/L) 1
• More severe fluid restriction plus albumin infusion for severe hyponatremia 1
• Avoid hypertonic saline unless life-threatening symptoms are present 1

Special Considerations

High-Risk Patients for Osmotic Demyelination

• Patients with advanced liver disease, alcoholism, malnutrition, or prior encephalopathy require more cautious correction (4-6 mmol/L per day) 1
• If overcorrection occurs, consider relowering with electrolyte-free water or desmopressin 1

Neurosurgical Patients

• Distinguish between SIADH and cerebral salt wasting (CSW) as treatment approaches differ significantly 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

Pharmacological Treatment with Tolvaptan

• Initiate only in a hospital setting where serum sodium can be monitored closely 2
• Starting dose is 15 mg once daily, can increase to 30 mg after 24 hours, maximum 60 mg daily 2
• Do not administer for more than 30 days to minimize risk of liver injury 2
• Contraindicated in ADPKD, hypovolemic hyponatremia, and patients taking strong CYP3A inhibitors 2

Monitoring and Follow-up

• For severe symptoms: monitor serum sodium every 2 hours during initial correction, then every 4 hours after resolution of severe symptoms 1
• For mild/moderate symptoms: monitor serum sodium daily 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 CSW (can worsen outcomes) 1
• Failing to recognize and treat the underlying cause 1
• Using hypertonic saline in hypervolemic hyponatremia without life-threatening symptoms 1