What is the management for an adult patient with hyponatremia (sodium level of 125 mmol/L)?

Management of Hyponatremia (Sodium 125 mmol/L)

For an adult patient with a sodium level of 125 mmol/L, the management approach depends critically on symptom severity and volume status, but this level warrants immediate evaluation and treatment as it represents moderate-to-severe hyponatremia associated with significant morbidity and mortality. 1

Immediate Assessment Required

Determine symptom severity first - this dictates urgency of correction 1:

• Severe symptoms (seizures, coma, altered mental status, respiratory distress): Medical emergency requiring immediate 3% hypertonic saline 1, 2
• Moderate symptoms (nausea, vomiting, confusion, headache, gait instability): Requires hospital admission with monitored correction 1
• Mild/asymptomatic: Can proceed with more conservative management based on volume status 1

Assess volume status through physical examination 1:

• Hypovolemic signs: Orthostatic hypotension, dry mucous membranes, decreased skin turgor, flat neck veins 1
• Euvolemic: No edema, normal blood pressure, normal skin turgor 1
• Hypervolemic signs: Peripheral edema, ascites, jugular venous distention, pulmonary congestion 1

Critical Correction Rate Guidelines

Never exceed 8 mmol/L correction in 24 hours to prevent osmotic demyelination syndrome 1, 2. This is the single most important safety principle.

• High-risk patients (advanced liver disease, alcoholism, malnutrition, prior encephalopathy): Limit to 4-6 mmol/L per day 1, 2
• Severe symptomatic cases: Initial goal of 6 mmol/L over 6 hours or until symptoms resolve, then stop to avoid exceeding 8 mmol/L total in 24 hours 1

Treatment Algorithm Based on Volume Status

For Hypovolemic Hyponatremia

Administer isotonic saline (0.9% NaCl) for volume repletion 1:

• Initial rate: 15-20 mL/kg/h, then 4-14 mL/kg/h based on response 1
• Discontinue any diuretics immediately 1
• Urine sodium <30 mmol/L predicts good response to saline (71-100% positive predictive value) 1
• Monitor sodium every 2-4 hours during active correction 1

For Euvolemic Hyponatremia (SIADH)

Fluid restriction to 1 L/day is the cornerstone of treatment 1, 2:

• If no response to fluid restriction, add oral sodium chloride 100 mEq three times daily 1
• For persistent cases, consider vasopressin receptor antagonists (tolvaptan 15 mg once daily, titrate to 30-60 mg) 1
• Alternative options: urea, demeclocycline, lithium (less commonly used due to side effects) 1, 2

For Hypervolemic Hyponatremia (Heart Failure, Cirrhosis)

Implement fluid restriction to 1-1.5 L/day 1, 2:

• Temporarily discontinue diuretics if sodium <125 mmol/L 1
• For cirrhotic patients: Consider albumin infusion alongside fluid restriction 1
• Avoid hypertonic saline unless life-threatening symptoms present - it worsens ascites and edema 1
• Sodium restriction (not fluid restriction) results in weight loss as fluid follows sodium 1

Emergency Management for Severe Symptoms

Administer 3% hypertonic saline immediately 1, 2, 3:

• Give as 100 mL boluses over 10 minutes, can repeat up to 3 times at 10-minute intervals until symptoms improve 1
• Target: Increase sodium by 6 mmol/L over first 6 hours or until severe symptoms resolve 1
• Calculate sodium deficit: Desired increase (mEq/L) × (0.5 × ideal body weight in kg) 1
• Monitor serum sodium every 2 hours during initial correction 1
• Once symptoms resolve, switch to slower correction to avoid exceeding 8 mmol/L total in 24 hours 1

Special Population Considerations

Neurosurgical patients: Distinguish between SIADH and cerebral salt wasting (CSW) 1:

• CSW requires volume and sodium replacement, NOT fluid restriction - using fluid restriction worsens outcomes 1
• CSW characteristics: True hypovolemia, CVP <6 cm H₂O, high urine sodium despite volume depletion 1
• Consider fludrocortisone 0.1-0.2 mg daily for severe symptoms or subarachnoid hemorrhage patients 1

Cirrhotic patients 1:

• Higher risk of osmotic demyelination syndrome - limit correction to 4-6 mmol/L per day 1
• Hyponatremia increases risk of spontaneous bacterial peritonitis (OR 3.40), hepatorenal syndrome (OR 3.45), and hepatic encephalopathy (OR 2.36) 1
• Tolvaptan carries higher risk of gastrointestinal bleeding in cirrhosis (10% vs 2% placebo) 1

Essential Monitoring

• Severe symptoms: Check sodium every 2 hours during initial correction 1
• Mild symptoms: Check sodium every 4 hours initially, then daily 1
• Watch for osmotic demyelination syndrome (dysarthria, dysphagia, oculomotor dysfunction, quadriparesis) typically occurring 2-7 days after rapid correction 1

Common Pitfalls to Avoid

• Never use fluid restriction for severe symptomatic hyponatremia - this is a medical emergency requiring hypertonic saline 1
• Never exceed 8 mmol/L correction in 24 hours - overcorrection causes osmotic demyelination syndrome 1, 2
• Never use fluid restriction in cerebral salt wasting - it worsens outcomes 1
• Never ignore mild hyponatremia (130-135 mmol/L) - it increases fall risk (21% vs 5%) and mortality (60-fold increase) 1
• Never use hypertonic saline in hypervolemic hyponatremia without life-threatening symptoms - it worsens fluid overload 1

Management of Overcorrection

If sodium correction exceeds 8 mmol/L in 24 hours 1:

• Immediately discontinue current fluids and switch to D5W (5% dextrose in water) 1
• Consider administering desmopressin to slow or reverse the rapid rise 1
• Target: Relower sodium to bring total 24-hour correction to ≤8 mmol/L from starting point 1