Hyponatremia Correction
Treatment Based on Symptom Severity
For severe symptomatic hyponatremia (seizures, coma, altered mental status), immediately administer 3% hypertonic saline with a target correction of 6 mmol/L over 6 hours or until symptoms resolve, with a maximum total correction of 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome. 1, 2
Severe Symptomatic Hyponatremia (Medical Emergency)
- Administer 3% hypertonic saline as 100 mL boluses over 10 minutes, repeatable up to three times at 10-minute intervals until symptoms improve 1
- Target correction: 4-6 mmol/L increase within 1-2 hours 3
- Never exceed 8 mmol/L correction in 24 hours (or 12 mmol/L maximum per FDA labeling for tolvaptan patients) 1, 2
- 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 (see below) 1, 4
- Correction rate: 4-8 mmol/L per day for average-risk patients 1
- Monitor serum sodium every 4-6 hours initially, then daily 1
Treatment Based on Volume Status
Hypovolemic Hyponatremia
- Discontinue diuretics immediately 1
- Administer isotonic saline (0.9% NaCl) for volume repletion 1, 4
- Urine sodium <30 mmol/L predicts good response to saline (positive predictive value 71-100%) 1
- Once euvolemic, reassess and adjust therapy based on sodium response 1
Euvolemic Hyponatremia (SIADH)
- Fluid restriction to 1 L/day is the cornerstone of treatment 1, 5
- If no response to fluid restriction after 24-48 hours, add oral sodium chloride 100 mEq three times daily 1
- For resistant cases, consider vasopressin receptor antagonists (tolvaptan 15 mg once daily, titrate to 30-60 mg) 1, 2
- Alternative pharmacological options: urea, demeclocycline, or loop diuretics 1, 3
Hypervolemic Hyponatremia (Heart Failure, Cirrhosis)
- Fluid restriction to 1-1.5 L/day for serum sodium <125 mmol/L 1, 4
- Discontinue diuretics temporarily if sodium <125 mmol/L 1
- For cirrhotic patients: consider albumin infusion (6-8 g per liter of ascites drained) 1
- Avoid hypertonic saline unless life-threatening symptoms present, as it worsens edema and ascites 1
- Tolvaptan may be considered for persistent severe hyponatremia despite fluid restriction, but use with extreme caution in cirrhosis due to increased gastrointestinal bleeding risk (10% vs 2% placebo) 1, 2
High-Risk Populations Requiring Slower 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, 2
- These patients have significantly higher risk of osmotic demyelination syndrome 1, 6
- Monitor even more frequently (every 2-4 hours initially) 1
- If overcorrection occurs, immediately switch to D5W and consider desmopressin to relower sodium 1
Special Considerations: Cerebral Salt Wasting (Neurosurgical Patients)
- Treatment focuses on volume and sodium replacement, NOT fluid restriction 1
- Distinguish from SIADH: CSW has true hypovolemia with low CVP, orthostatic hypotension, dry mucous membranes 1
- Administer isotonic or hypertonic saline based on severity 1
- For 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
Critical Pitfalls to Avoid
- Overly rapid correction (>8 mmol/L in 24 hours) causes osmotic demyelination syndrome with dysarthria, dysphagia, quadriparesis, seizures, or death 1, 2, 6
- Using fluid restriction in cerebral salt wasting worsens outcomes 1
- Inadequate monitoring during active correction 1
- Using hypertonic saline in hypervolemic hyponatremia without life-threatening symptoms 1
- Failing to distinguish SIADH from cerebral salt wasting in neurosurgical patients 1
- Ignoring mild hyponatremia (130-135 mmol/L), which increases fall risk (21% vs 5%) and mortality 1, 3