What is the treatment for hyponatremia (low sodium levels)?

Treatment of Hyponatremia

Hyponatremia treatment must be guided by symptom severity, volume status, and correction rate limits to prevent osmotic demyelination syndrome while addressing the underlying cause. 1

Initial Assessment

Before initiating treatment, rapidly assess three critical factors:

• Symptom severity: Determine if the patient has severe symptoms (seizures, coma, altered consciousness, respiratory distress) requiring emergency intervention, or mild symptoms (nausea, headache, weakness) 1, 2
• Volume status: Classify as hypovolemic (orthostatic hypotension, dry mucous membranes, decreased skin turgor), euvolemic (no edema, normal blood pressure), or hypervolemic (peripheral edema, ascites, jugular venous distention) 1
• Serum and urine studies: Obtain serum osmolality, urine osmolality, and urine sodium to determine the underlying etiology 1

Treatment Based on Symptom Severity

Severe Symptomatic Hyponatremia (Medical Emergency)

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

• Administer 3% hypertonic saline as 100 mL boluses over 10 minutes, which can be repeated up to three times at 10-minute intervals until symptoms improve 1
• Critical safety limit: Total correction must not exceed 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome 1, 3
• Monitor serum sodium every 2 hours during initial correction 1
• Consider ICU admission for close monitoring 1

Mild to Moderate Symptomatic or Asymptomatic Hyponatremia

Treatment depends on volume status and underlying cause:

Treatment Based on Volume Status

Hypovolemic Hyponatremia

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

• Urine sodium <30 mmol/L predicts good response to saline infusion (positive predictive value 71-100%) 1
• Once euvolemic, reassess and adjust treatment based on sodium response 1
• Correction rate should not exceed 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, consider pharmacological options:
  • Tolvaptan (vasopressin V2 receptor antagonist): Start 15 mg once daily, titrate to 30-60 mg as needed 3
  • Urea, demeclocycline, or lithium for resistant cases 1
• For severe symptoms, use 3% hypertonic saline as described above 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
• In cirrhotic patients, consider albumin infusion alongside fluid restriction 1
• Avoid hypertonic saline unless life-threatening symptoms are present, as it may worsen ascites and edema 1
• For persistent hyponatremia despite fluid restriction, consider tolvaptan with extreme caution in cirrhosis due to increased risk of gastrointestinal bleeding (10% vs 2% placebo) 1

Special Populations Requiring Cautious Correction

Patients with advanced liver disease, alcoholism, malnutrition, or prior encephalopathy require more cautious correction at 4-6 mmol/L per day, not exceeding 8 mmol/L in 24 hours. 1, 3

These high-risk patients are more susceptible to osmotic demyelination syndrome even at standard correction rates 1.

Neurosurgical Patients: Distinguishing SIADH from Cerebral Salt Wasting

In neurosurgical patients, cerebral salt wasting (CSW) is more common than SIADH and requires fundamentally different treatment. 1

• CSW treatment: Volume and sodium replacement with isotonic or hypertonic saline, NOT fluid restriction 1
  • For severe symptoms, use 3% hypertonic saline plus fludrocortisone in ICU 1
  • Consider hydrocortisone to prevent natriuresis in subarachnoid hemorrhage patients 1
• SIADH treatment: Fluid restriction as described above 1
• Critical pitfall: Using fluid restriction in CSW worsens outcomes 1
• In subarachnoid hemorrhage patients at risk of vasospasm, avoid fluid restriction 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 in serum sodium 1
• Monitor for signs of osmotic demyelination syndrome (dysarthria, dysphagia, oculomotor dysfunction, quadriparesis) typically occurring 2-7 days after rapid correction 1, 3

Common Pitfalls to Avoid

• Overly rapid correction exceeding 8 mmol/L in 24 hours leading to osmotic demyelination syndrome 1
• Inadequate monitoring during active correction 1
• Using fluid restriction in cerebral salt wasting 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—even mild chronic hyponatremia increases fall risk (21% vs 5%) and mortality (60-fold increase) 1, 2

Monitoring Requirements

• Severe symptoms: Monitor serum sodium every 2 hours during initial correction 1
• After resolution of severe symptoms: Monitor every 4 hours 1
• Mild symptoms or asymptomatic: Monitor daily initially, then adjust frequency based on response 1
• Track daily weight and fluid balance meticulously 1