How to manage severe hyponatremia (low sodium level)?

Management of Severe Hyponatremia (Sodium 117 mmol/L)

The treatment of severe hyponatremia with sodium level of 117 mmol/L requires careful correction based on the patient's volume status, with a maximum correction rate of 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome. 1

Initial Assessment

• Determine the patient's volume status (hypovolemic, euvolemic, or hypervolemic) as this guides appropriate treatment 1
• Check urine osmolality and sodium concentration to help distinguish between different causes of hyponatremia 1
• Assess for symptoms: mild (nausea, weakness, headache) vs. severe (seizures, confusion, coma) 2

Treatment Based on Volume Status

For Hypovolemic Hyponatremia:

• Discontinue diuretics if they are contributing to hyponatremia 1
• Administer isotonic (0.9%) saline for volume repletion 1
• Once euvolemia is achieved, reassess sodium levels to guide further management 1

For Euvolemic Hyponatremia (e.g., SIADH):

• Implement fluid restriction to 1 L/day as first-line treatment 1
• Consider oral sodium chloride supplementation at 100 mEq three times daily if fluid restriction alone is insufficient 3
• For persistent cases, consider pharmacological options such as tolvaptan (vasopressin receptor antagonist) 4

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

• Implement fluid restriction to 1-1.5 L/day 1
• Consider albumin infusion, particularly in patients with cirrhosis 1
• Avoid hypertonic saline unless life-threatening symptoms are present, as it may worsen edema and ascites 1

Correction Rate Guidelines

• For severe symptomatic hyponatremia (seizures, coma): administer 3% hypertonic saline with a goal to correct by 6 mmol/L over 6 hours or until severe symptoms resolve 1
• Total correction should not exceed 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome 1
• For patients with advanced liver disease, alcoholism, malnutrition, or prior encephalopathy: use more cautious correction rates (4-6 mmol/L per day) 1

Monitoring During Treatment

• Monitor serum sodium every 2-4 hours during initial correction for severe symptoms 1
• Calculate sodium deficit using formula: Desired increase in Na (mEq/L) × (0.5 × ideal body weight in kg) 1
• Watch for signs of osmotic demyelination syndrome (dysarthria, dysphagia, quadriparesis) typically occurring 2-7 days after rapid correction 1

Special Considerations

• If overcorrection occurs, consider relowering with electrolyte-free water or desmopressin 1
• In neurosurgical patients, distinguish between SIADH and cerebral salt wasting, as treatment approaches differ significantly 1
• For patients with cirrhosis, fluid restriction is generally recommended, but may be less effective alone 5

Common Pitfalls to Avoid

• Overly rapid correction exceeding 8 mmol/L in 24 hours can lead to osmotic demyelination syndrome 1
• Inadequate monitoring during active correction 1
• Using fluid restriction in cerebral salt wasting can worsen outcomes 1
• Failing to recognize and treat the underlying cause 1
• Using hypertonic saline in hypervolemic hyponatremia without life-threatening symptoms 1

Remember that even mild chronic hyponatremia is associated with cognitive impairment, gait disturbances, and increased rates of falls and fractures, so appropriate treatment is essential 6.