How to correct severe hyponatremia (low sodium levels)?

Correcting Severe Hyponatremia

For severe symptomatic hyponatremia (sodium <120 mEq/L with neurological symptoms like seizures, altered mental status, or coma), immediately administer 3% hypertonic saline with a target correction of 6 mmol/L over the first 6 hours or until symptoms resolve, but never exceed 8 mmol/L total correction in 24 hours to prevent osmotic demyelination syndrome. 1

Initial Assessment and Classification

Before initiating treatment, determine three critical factors:

• Symptom severity: Severe symptoms (seizures, coma, altered consciousness) versus mild symptoms (nausea, headache, confusion) versus asymptomatic 1, 2
• Acuity: Acute (<48 hours) versus chronic (>48 hours) onset 1
• Volume status: Hypovolemic, euvolemic, or hypervolemic 1

Obtain serum and urine osmolality, urine sodium, and assess extracellular fluid volume status immediately 1, 3

Treatment Based on Symptom Severity

Severe Symptomatic Hyponatremia (Medical Emergency)

This is a life-threatening emergency requiring immediate intervention 1, 4:

• Administer 3% hypertonic saline immediately 1, 3
• Target: Increase sodium by 6 mmol/L over 6 hours or until severe symptoms resolve 1
• Calculate infusion rate: Body weight (kg) × desired rate of increase (mmol/L/hour) 3
• Maximum correction limit: 8 mmol/L in 24 hours 1, 5, 4
• Monitor sodium every 2 hours during initial correction 1

After achieving 6 mmol/L correction in 6 hours, only 2 mmol/L additional correction is permitted in the remaining 18 hours 1

Asymptomatic or Mildly Symptomatic Hyponatremia

Treatment depends on volume status 1:

• Hypovolemic: Discontinue diuretics and administer isotonic saline (0.9% NaCl) for volume repletion 1
• Euvolemic (SIADH): Fluid restriction to 1 L/day as first-line treatment 1, 3
• Hypervolemic (cirrhosis, heart failure): Fluid restriction to 1-1.5 L/day for sodium <125 mmol/L 1

Critical Correction Rate Guidelines

The single most important safety parameter is avoiding overcorrection 1, 5:

• Standard patients: Maximum 8 mmol/L per 24 hours 1, 4
• High-risk patients (advanced liver disease, alcoholism, malnutrition, prior encephalopathy): Maximum 4-6 mmol/L per day 1

Exceeding these limits risks osmotic demyelination syndrome, which causes dysarthria, dysphagia, quadriparesis, seizures, coma, or death 1, 5

Treatment Based on Underlying Cause

SIADH (Euvolemic)

• Primary treatment: Fluid restriction to 1 L/day 1
• If no response: Add oral sodium chloride 100 mEq three times daily 1
• For severe symptoms: 3% hypertonic saline with careful monitoring 1

Cerebral Salt Wasting (Hypovolemic)

• Primary treatment: Volume and sodium replacement with isotonic or hypertonic saline 1
• For severe symptoms: 3% hypertonic saline plus fludrocortisone 1
• Critical pitfall: Never use fluid restriction in cerebral salt wasting—this worsens outcomes 1

Hypervolemic Hyponatremia (Cirrhosis, Heart Failure)

• Fluid restriction: 1-1.5 L/day for sodium <125 mmol/L 1
• Discontinue diuretics temporarily if sodium <125 mmol/L 1
• Consider albumin infusion in cirrhotic patients 1
• Avoid hypertonic saline unless life-threatening symptoms present 1

Monitoring Protocol

During active correction 1:

• Severe symptoms: Check sodium every 2 hours
• After symptom resolution: Check every 4 hours
• Watch for overcorrection: If exceeds 8 mmol/L in 24 hours, immediately switch to D5W and consider desmopressin 1

Common Pitfalls to Avoid

• Overly rapid correction exceeding 8 mmol/L in 24 hours leads to osmotic demyelination syndrome 1
• 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
• Ignoring mild hyponatremia (130-135 mmol/L) as clinically insignificant—it increases fall risk and mortality 60-fold 1, 4

Special Populations

Patients requiring more cautious correction (4-6 mmol/L per day) 1:

• Advanced liver disease
• Chronic alcoholism
• Severe malnutrition
• Prior encephalopathy
• Baseline sodium <105 mmol/L 6

When to Discontinue 3% Hypertonic Saline

Stop 3% saline when 7:

• Severe symptoms resolve
• 6 mmol/L correction achieved in first 6 hours
• Total correction approaches 8 mmol/L in 24 hours

Then transition to fluid restriction (1 L/day) and monitor sodium every 4 hours instead of every 2 hours 7