How to manage hyponatremia in the Emergency Department (ED)?

Management of Hyponatremia in the Emergency Department

For a patient with sodium of 132 mEq/L in the ED, treatment should be initiated with careful assessment of volume status and symptom severity, followed by targeted therapy based on the underlying cause. 1

Initial Assessment

• Hyponatremia should be further investigated and treated when serum sodium is less than 131 mmol/L, though even mild hyponatremia (132 mmol/L) warrants attention 2, 1
• Evaluate volume status (hypovolemic, euvolemic, or hypervolemic) through physical examination, basic laboratory studies, and invasive monitoring when available 2
• Check urine sodium concentration and osmolality to help determine the underlying cause 1
• Assess symptom severity, as this will guide treatment approach and correction rate 1

Treatment Based on Volume Status

Hypovolemic Hyponatremia

• Discontinue diuretics if they are contributing to hyponatremia 1
• Administer isotonic (0.9%) saline for volume repletion 1
• For severe dehydration with neurological symptoms, consider hypertonic saline with careful monitoring 1

Euvolemic Hyponatremia (SIADH)

• Implement fluid restriction to 1L/day for mild/asymptomatic cases 1
• For moderate hyponatremia (120-125 mEq/L), consider oral sodium chloride 100 mEq three times daily 3
• Consider urea, diuretics, lithium, or demeclocycline for resistant cases 2, 1

Hypervolemic Hyponatremia (e.g., cirrhosis, heart failure)

• Implement fluid restriction to 1-1.5 L/day for serum sodium <125 mmol/L 1
• Consider albumin infusion for patients with cirrhosis 1
• Avoid hypertonic saline unless life-threatening symptoms are present 1

Treatment Based on Symptom Severity

Severe Symptoms (seizures, coma)

• Administer 3% hypertonic saline with an initial goal to correct 6 mmol/L over 6 hours or until severe symptoms resolve 1
• Consider ICU admission for close monitoring during treatment 1

Mild to Moderate Symptoms

• Implement fluid restriction and treat the underlying cause 1
• Monitor serum sodium levels every 4-6 hours during initial correction 3

Correction Rate Guidelines

• Do not exceed correction of 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome 2, 1
• For patients with advanced liver disease, alcoholism, malnutrition, or prior encephalopathy, use more cautious correction rates (4-6 mmol/L per day) 1
• Calculate sodium deficit using formula: Desired increase in Na (mEq/L) × (0.5 × ideal body weight in kg) 1

Special Considerations for 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 rather than fluid restriction 2, 1
• Consider fludrocortisone for hyponatremia in subarachnoid hemorrhage patients at risk of vasospasm 2
• Avoid fluid restriction in subarachnoid hemorrhage patients at risk of vasospasm 2

Monitoring and Follow-up

• Monitor serum sodium levels frequently during correction (every 2-4 hours for severe cases) 1
• Watch for signs of osmotic demyelination syndrome (dysarthria, dysphagia, oculomotor dysfunction, quadriparesis) 1
• If overcorrection occurs, consider relowering with electrolyte-free water or desmopressin 1

Common Pitfalls to Avoid

• Overly rapid correction 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

For a patient with sodium of 132 mEq/L in the ED, careful assessment of volume status and symptoms is essential before initiating targeted therapy. While this level is only mildly decreased, treatment should focus on identifying and addressing the underlying cause while monitoring for clinical deterioration.