How to correct severe hyponatremia (sodium level of 113 mmol/L) in a stable patient with normal vitals?

Management of Severe Hyponatremia (Na 113 mmol/L) in a Stable Patient

For a stable patient with severe hyponatremia (Na 113 mmol/L) and normal vitals, the priority is determining volume status and symptom severity to guide treatment, with the critical safety principle being to never exceed 8 mmol/L correction in 24 hours to prevent osmotic demyelination syndrome. 1

Initial Assessment

Determine volume status immediately through physical examination, though recognize this has limited accuracy (sensitivity 41.1%, specificity 80%) 1:

• Hypovolemic signs: orthostatic hypotension, dry mucous membranes, decreased skin turgor, flat neck veins 1
• Euvolemic signs: normal volume status, no edema, normal blood pressure 1
• Hypervolemic signs: peripheral edema, ascites, jugular venous distention 1

Obtain essential laboratory tests 1:

• Serum osmolality (to exclude pseudohyponatremia)
• Urine osmolality and urine sodium concentration
• Serum uric acid (<4 mg/dL suggests SIADH with 73-100% positive predictive value) 1
• Thyroid function (TSH) and cortisol to exclude hypothyroidism/adrenal insufficiency 1

Treatment Based on Volume Status

If Hypovolemic (Urine Na <30 mmol/L)

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

• Initial infusion rate: 15-20 mL/kg/h, then 4-14 mL/kg/h based on response 1
• Discontinue any diuretics immediately 1
• Target correction: 4-6 mmol/L per day, maximum 8 mmol/L in 24 hours 1
• Check sodium every 4 hours initially 1

If Euvolemic (SIADH suspected)

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

• If no response after 24-48 hours, add oral sodium chloride 100 mEq three times daily 1
• Consider urea or demeclocycline for resistant cases 1
• Avoid hypertonic saline unless patient develops severe symptoms (seizures, altered mental status) 1
• Target correction: 4-6 mmol/L per day, maximum 8 mmol/L in 24 hours 1

If Hypervolemic (Heart failure, cirrhosis)

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

• Discontinue diuretics temporarily if sodium <125 mmol/L 1
• For cirrhotic patients, consider albumin infusion alongside fluid restriction 1
• Avoid hypertonic saline unless life-threatening symptoms develop, as it worsens ascites and edema 1
• Target correction: 4-6 mmol/L per day, maximum 8 mmol/L in 24 hours 1

Critical Correction Rate Guidelines

The single most important safety principle: never exceed 8 mmol/L correction in 24 hours 1, 2:

• Standard correction rate: 4-6 mmol/L per day 1
• High-risk patients (advanced liver disease, alcoholism, malnutrition, prior encephalopathy): limit to 4-6 mmol/L per day, absolute maximum 8 mmol/L in 24 hours 1
• Correction exceeding 12 mmol/L in 24 hours risks osmotic demyelination syndrome with dysarthria, dysphagia, quadriparesis, seizures, coma, or death 2, 3

Monitoring Protocol

For asymptomatic or mildly symptomatic patients 1:

• Check sodium every 4-6 hours during initial correction
• Once stable, check daily
• Monitor for signs of overcorrection

If overcorrection occurs (>8 mmol/L in 24 hours) 1:

• Immediately discontinue current fluids
• Switch to D5W (5% dextrose in water)
• Consider desmopressin to slow or reverse rapid rise
• This is a medical emergency requiring immediate intervention

When to Use Hypertonic Saline (3%)

Reserve 3% hypertonic saline ONLY for severe symptomatic hyponatremia 1, 4:

• Seizures, coma, altered mental status, or cardiorespiratory distress
• Not indicated for this stable patient with normal vitals
• If needed: administer 100 mL bolus over 10 minutes, can repeat up to 3 times 1
• Target: 6 mmol/L increase over first 6 hours or until symptoms resolve 1

Common Pitfalls to Avoid

• Never correct chronic hyponatremia faster than 8 mmol/L in 24 hours - this causes osmotic demyelination syndrome 1, 3
• Do not use fluid restriction in hypovolemic patients - this worsens outcomes 1
• Do not use hypertonic saline in hypervolemic patients without life-threatening symptoms - it worsens fluid overload 1
• Do not ignore mild hyponatremia - even levels of 130-135 mmol/L increase fall risk and mortality 1, 5
• Inadequate monitoring during active correction is dangerous 1

Special Considerations

For neurosurgical patients, distinguish between SIADH and cerebral salt wasting (CSW) 1:

• CSW requires volume and sodium replacement, NOT fluid restriction
• Consider fludrocortisone 0.1-0.2 mg daily for CSW 1

For cirrhotic patients 1:

• Hyponatremia increases risk of spontaneous bacterial peritonitis (OR 3.40), hepatorenal syndrome (OR 3.45), and hepatic encephalopathy (OR 2.36)
• Require even more cautious correction (4-6 mmol/L per day maximum)
• Sodium restriction (not fluid restriction) results in weight loss as fluid follows sodium

Tolvaptan (vaptan) considerations 2:

• FDA-approved for euvolemic/hypervolemic hyponatremia
• Must be initiated in hospital with close sodium monitoring
• Starting dose: 15 mg once daily, can titrate to 30-60 mg
• Avoid fluid restriction during first 24 hours of tolvaptan therapy 2
• Higher risk of gastrointestinal bleeding in cirrhosis (10% vs 2% placebo) 1
• Limit use to maximum 30 days to minimize liver injury risk 2