What is the treatment for a patient with hyponatremia (sodium level of 128 mmol/L)?

Treatment of Hyponatremia (Sodium 128 mmol/L)

For a sodium level of 128 mmol/L, continue current management with close monitoring of serum electrolytes, as this represents mild hyponatremia that typically does not require aggressive intervention unless symptomatic. 1

Initial Assessment

The first critical step is determining volume status and symptom severity, as these dictate treatment approach 1:

• Assess for symptoms: Nausea, vomiting, headache, weakness indicate mild symptoms; confusion, seizures, altered mental status indicate severe symptoms requiring emergency treatment 2, 3
• Determine volume status through physical examination: look for orthostatic hypotension, dry mucous membranes (hypovolemic); peripheral edema, ascites, jugular venous distention (hypervolemic); or absence of these findings (euvolemic) 1
• Obtain urine sodium and osmolality: Urine sodium <30 mmol/L suggests hypovolemia; >20-40 mmol/L with high urine osmolality suggests SIADH 1

Treatment Based on Volume Status

Hypovolemic Hyponatremia

• Discontinue diuretics immediately if contributing to sodium loss 1
• Administer isotonic saline (0.9% NaCl) for volume repletion at 15-20 mL/kg/h initially, then 4-14 mL/kg/h based on response 1
• Urine sodium <30 mmol/L predicts 71-100% response to saline infusion 1

Euvolemic Hyponatremia (SIADH)

• Implement fluid restriction to 1 L/day as first-line treatment 1, 4
• If no response after 24-48 hours, add oral sodium chloride 100 mEq three times daily (total ~7 grams sodium/day) 1, 4
• Consider urea or vaptans (tolvaptan 15 mg daily) for resistant cases 1, 3

Hypervolemic Hyponatremia (Heart Failure, Cirrhosis)

• Implement fluid restriction to 1-1.5 L/day for sodium <125 mmol/L 1
• Temporarily discontinue diuretics if sodium drops below 125 mmol/L 5, 1
• For cirrhotic patients, consider albumin infusion alongside fluid restriction 1
• Avoid hypertonic saline unless life-threatening symptoms present, as it worsens edema and ascites 1

Critical Correction Rate Guidelines

The maximum correction rate must never exceed 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome 1, 6, 3:

• Target correction: 4-6 mmol/L per day for most patients 1
• High-risk patients (cirrhosis, alcoholism, malnutrition, advanced liver disease): limit to 4-6 mmol/L per day, maximum 8 mmol/L in 24 hours 1, 6
• Monitor serum sodium every 24-48 hours initially during correction 1

When to Use Hypertonic Saline (3%)

Reserve 3% hypertonic saline ONLY for severe symptomatic hyponatremia with seizures, coma, or altered mental status 1, 2:

• Administer as 100-150 mL bolus over 10 minutes, repeatable up to 3 times 1
• Target: increase sodium by 6 mmol/L over 6 hours or until symptoms resolve 1, 4
• Never exceed 8 mmol/L total correction in 24 hours 1, 6
• Requires hospital admission with ICU-level monitoring 6

Monitoring Requirements

• Check serum sodium every 4-6 hours during active correction 4
• Monitor for signs of osmotic demyelination syndrome: dysarthria, dysphagia, oculomotor dysfunction, quadriparesis (typically 2-7 days post-correction) 1
• Track daily weights: aim for 0.5 kg/day loss without edema, 1 kg/day with edema 5

Common Pitfalls to Avoid

• Never ignore mild hyponatremia (130-135 mmol/L) as it increases fall risk (21% vs 5%) and mortality (60-fold increase with sodium <130 mmol/L) 1, 3
• Never use fluid restriction in cerebral salt wasting (neurosurgical patients)—this worsens outcomes; these patients need volume and sodium replacement 1
• Never correct chronic hyponatremia faster than 8 mmol/L in 24 hours—overcorrection causes osmotic demyelination syndrome 1, 6, 7
• Never use hypertonic saline in hypervolemic hyponatremia without life-threatening symptoms 1
• Never stop diuretics in heart failure patients with mild hyponatremia (126-135 mmol/L) if they have volume overload—continue diuretics with close monitoring 1

Special Populations

Cirrhotic Patients

• Hyponatremia increases risk of spontaneous bacterial peritonitis (OR 3.40), hepatorenal syndrome (OR 3.45), and hepatic encephalopathy (OR 2.36) 1
• Sodium restriction (not fluid restriction) causes weight loss as fluid follows sodium 1
• Require more cautious correction: 4-6 mmol/L per day maximum 5, 1

Neurosurgical Patients

• Distinguish SIADH from cerebral salt wasting (CSW): CSW requires volume/sodium replacement with normal saline or hypertonic saline plus fludrocortisone 0.1-0.2 mg daily; SIADH requires fluid restriction 1
• Never use fluid restriction in subarachnoid hemorrhage patients at risk of vasospasm 1