What are the treatment options for hyponatremia?

Treatment of Hyponatremia

The treatment of hyponatremia must be guided by three critical factors: symptom severity, volume status (hypovolemic, euvolemic, or hypervolemic), and correction rate limits to prevent osmotic demyelination syndrome. 1

Immediate Assessment

Determine the following before initiating treatment:

• Symptom severity: Severe symptoms (seizures, coma, altered consciousness, respiratory distress) require immediate hypertonic saline; mild symptoms (nausea, headache, weakness) allow for more conservative management 1, 2
• Volume status: Assess for orthostatic hypotension, dry mucous membranes (hypovolemic); peripheral edema, ascites, jugular venous distention (hypervolemic); or absence of these findings (euvolemic) 1
• Serum and urine osmolality, urine sodium, and urine electrolytes to determine underlying etiology 1

Treatment Based on Symptom Severity

Severe Symptomatic Hyponatremia (Medical Emergency)

For patients with seizures, coma, or severe neurological symptoms, immediately administer 3% hypertonic saline with a target correction of 6 mmol/L over 6 hours or until symptoms resolve. 1

• Administer 3% hypertonic saline as 100 mL boluses over 10 minutes, repeatable up to three times at 10-minute intervals 1
• Never exceed 8 mmol/L total correction in 24 hours to prevent osmotic demyelination syndrome 1
• Monitor serum sodium every 2 hours during initial correction 1
• ICU admission is recommended for close monitoring 1

Mild to Moderate Symptomatic or Asymptomatic Hyponatremia

Treatment depends on volume status:

Treatment Based on Volume Status

Hypovolemic Hyponatremia

Discontinue diuretics immediately and administer isotonic saline (0.9% NaCl) for volume repletion. 1

• Initial infusion rate: 15-20 mL/kg/h, then 4-14 mL/kg/h based on response 1
• Urine sodium <30 mmol/L predicts good response to saline (positive predictive value 71-100%) 1
• Correction rate: maximum 8 mmol/L in 24 hours 1

Euvolemic Hyponatremia (SIADH)

Fluid restriction to 1 L/day is the cornerstone of treatment for SIADH. 1

• If no response to fluid restriction, add oral sodium chloride 100 mEq three times daily 1
• For persistent cases despite fluid restriction, consider:
  • Tolvaptan 15 mg once daily (vasopressin receptor antagonist), titrating to 30-60 mg as needed 3, 1
  • Urea 15-30 g/day in divided doses 1
  • Demeclocycline or lithium (less commonly used due to side effects) 1
• Monitor serum sodium every 24 hours initially 1

Hypervolemic Hyponatremia (Heart Failure, Cirrhosis)

Implement fluid restriction to 1-1.5 L/day for serum sodium <125 mmol/L. 1

• Discontinue diuretics temporarily if sodium <125 mmol/L 1
• For cirrhotic patients, consider albumin infusion alongside fluid restriction 1
• Avoid hypertonic saline unless life-threatening symptoms are present, as it worsens edema and ascites 1
• For persistent hyponatremia despite fluid restriction and maximized guideline-directed therapy, consider tolvaptan 15 mg once daily 1, 3
• Caution: Tolvaptan in cirrhosis carries higher risk of gastrointestinal bleeding (10% vs 2% placebo) 1

Critical Correction Rate Guidelines

The single most important safety principle: never exceed 8 mmol/L correction in 24 hours. 1

Standard Correction Rates:

• Average risk patients: 4-8 mmol/L per day, maximum 10-12 mmol/L in 24 hours 1
• High-risk patients (advanced liver disease, alcoholism, malnutrition, prior encephalopathy): 4-6 mmol/L per day, maximum 8 mmol/L in 24 hours 1

Monitoring During Correction:

• Severe symptoms: check serum sodium every 2 hours 1
• After symptom resolution: check every 4 hours 1
• Asymptomatic patients: check every 24 hours initially 1

Management of Overcorrection

If sodium correction exceeds 8 mmol/L in 24 hours:

• Immediately discontinue current fluids and switch to D5W (5% dextrose in water) 1
• Consider administering desmopressin to slow or reverse the rapid rise 1
• Watch for signs of osmotic demyelination syndrome (dysarthria, dysphagia, oculomotor dysfunction, quadriparesis) typically occurring 2-7 days after rapid correction 1

Special Populations

Neurosurgical Patients

Distinguish between SIADH and cerebral salt wasting (CSW), as treatment approaches are opposite. 1

• SIADH: Euvolemic, treat with fluid restriction 1
• CSW: Hypovolemic (CVP <6 cm H₂O), treat with volume and sodium replacement using isotonic or hypertonic saline, NOT fluid restriction 1
• For CSW with severe symptoms: 3% hypertonic saline plus fludrocortisone 0.1-0.2 mg daily 1
• Never use fluid restriction in subarachnoid hemorrhage patients at risk of vasospasm 1

Cirrhotic Patients

• Hyponatremia increases risk of spontaneous bacterial peritonitis (OR 3.40), hepatorenal syndrome (OR 3.45), and hepatic encephalopathy (OR 2.36) 1
• Use more cautious correction rates (4-6 mmol/L per day) 1
• Sodium levels 130-135 mmol/L are often tolerated without specific treatment in chronic cases 1

Common Pitfalls to Avoid

• Overly rapid correction (>8 mmol/L in 24 hours) causes osmotic demyelination syndrome 1
• Using fluid restriction in cerebral salt wasting worsens outcomes 1
• Inadequate monitoring during active correction 1
• Failing to recognize and treat the underlying cause 1
• Using hypertonic saline in hypervolemic hyponatremia without life-threatening symptoms 1
• Ignoring mild hyponatremia (130-135 mmol/L) as clinically insignificant—it increases fall risk (21% vs 5%) and mortality (60-fold increase with sodium <130 mmol/L) 1, 2