Treatment of Hyponatremia
The treatment of hyponatremia should be based on the patient's volume status, severity of symptoms, and underlying cause, with careful attention to correction rates to prevent osmotic demyelination syndrome. 1
Initial Assessment
Hyponatremia is defined as serum sodium <135 mmol/L and should be classified by:
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
- Maximum correction should not exceed 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome 1, 2
- Monitor serum sodium every 2 hours during initial correction 1
- Patients with advanced liver disease, alcoholism, malnutrition require more cautious correction (4-6 mmol/L per day) 1
Mild to Moderate Symptomatic Hyponatremia
- Treatment depends on volume status (see below) 1, 2
- Correction rate should not exceed 8 mmol/L in 24 hours 1
Treatment Based on Volume Status
Hypovolemic Hyponatremia
- Discontinue diuretics and administer isotonic saline (0.9% NaCl) for volume repletion 1, 3
- For severe dehydration with neurological symptoms, consider hypertonic saline with careful monitoring 1
Euvolemic Hyponatremia (SIADH)
- Fluid restriction to 1 L/day is the cornerstone of treatment for mild/asymptomatic cases 1, 2
- Add oral sodium chloride 100 mEq three times daily if no response to fluid restriction 1
- For resistant cases, consider:
Hypervolemic Hyponatremia (cirrhosis, heart failure)
- Fluid restriction to 1-1.5 L/day for serum sodium <125 mmol/L 5, 1
- Consider albumin infusion for patients with cirrhosis 1
- Avoid hypertonic saline unless life-threatening symptoms are present 1
- Temporarily discontinue diuretics if sodium <125 mmol/L 1
- For refractory ascites, midodrine may be considered on a case-by-case basis 5
Special Considerations
Cirrhosis
- Patients with cirrhosis require more cautious correction (4-6 mmol/L per day) 1
- Hyponatremia in cirrhosis increases risk for hepatic encephalopathy, hepatorenal syndrome, and spontaneous bacterial peritonitis 1
- For ascites management with hyponatremia:
- Spironolactone monotherapy (starting dose 100 mg, increased to 400 mg) for first presentation of moderate ascites 5
- Combination therapy with spironolactone and furosemide for recurrent severe ascites 5
- Large volume paracentesis with albumin infusion (6-8 g per liter of ascites drained) for refractory ascites 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
- Consider fludrocortisone for hyponatremia in subarachnoid hemorrhage patients at risk of vasospasm 1
- Avoid fluid restriction in subarachnoid hemorrhage patients at risk of vasospasm 1
Monitoring and Prevention of Complications
- Monitor serum sodium levels regularly during correction 1
- If overcorrection occurs, consider relowering with electrolyte-free water or desmopressin 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, 2
- Inadequate monitoring during active correction 1
- Using fluid restriction in cerebral salt wasting 1
- Failing to recognize and treat the underlying cause 1, 6
- Using hypertonic saline in hypervolemic hyponatremia without life-threatening symptoms 1