What is the appropriate treatment for an adult patient with hyponatremia of 124 mmol/L?

Treatment of Hyponatremia with Sodium Level of 124 mmol/L

For a patient with hyponatremia of 124 mmol/L, you should NOT use hypertonic saline (3% NaCl) unless the patient has severe neurological symptoms such as seizures, coma, or altered mental status. Instead, treatment depends critically on the patient's volume status and symptom severity 1.

Initial Assessment Required

Before initiating treatment, you must determine three critical factors:

• Volume status: Assess for signs of hypovolemia (orthostatic hypotension, dry mucous membranes, decreased skin turgor), euvolemia, or hypervolemia (peripheral edema, ascites, jugular venous distention) 1
• Symptom severity: Mild symptoms include nausea, headache, weakness; severe symptoms include confusion, seizures, coma, or altered consciousness 2, 3
• Chronicity: Acute (<48 hours) versus chronic (>48 hours) onset, as this determines safe correction rates 1

Treatment Algorithm Based on Volume Status

For Hypovolemic Hyponatremia

• Administer isotonic saline (0.9% NaCl) for volume repletion, with initial infusion rate of 15-20 mL/kg/h 1, 3
• Discontinue any diuretics immediately 1
• Urine sodium <30 mmol/L predicts good response to saline with 71-100% positive predictive value 1

For Euvolemic Hyponatremia (SIADH)

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

For Hypervolemic Hyponatremia (Heart Failure, Cirrhosis)

• Implement fluid restriction to 1-1.5 L/day 1, 3
• Temporarily discontinue diuretics if sodium <125 mmol/L 1
• Consider albumin infusion in cirrhotic patients 1
• Avoid hypertonic saline unless life-threatening symptoms are present, as it worsens fluid overload 1

Critical Correction Rate Guidelines

The maximum correction rate must not exceed 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome 1, 5. This is the single most important safety principle.

• For average-risk patients: aim for 4-8 mmol/L per day 1
• For high-risk patients (advanced liver disease, alcoholism, malnutrition): limit to 4-6 mmol/L per day 1, 5
• Monitor serum sodium every 4-6 hours initially during active correction 1

When to Use Hypertonic Saline (3% NaCl)

Reserve 3% hypertonic saline ONLY for severe symptomatic hyponatremia with neurological emergencies 1, 3:

• Seizures, coma, or altered mental status requiring immediate intervention 1
• Administer as 100-150 mL bolus over 10 minutes, can repeat up to 3 times 1, 6
• Target correction of 6 mmol/L over first 6 hours or until severe symptoms resolve 1
• Total correction still must not exceed 8 mmol/L in 24 hours 1, 5

Common Pitfalls to Avoid

• Never correct chronic hyponatremia faster than 8 mmol/L in 24 hours—this causes osmotic demyelination syndrome with devastating neurological consequences including dysarthria, dysphagia, quadriparesis, or death 1, 5
• Do not use hypertonic saline in asymptomatic or mildly symptomatic patients—this risks overcorrection 1
• Avoid fluid restriction in cerebral salt wasting (common in neurosurgical patients)—this worsens outcomes 1
• Do not ignore mild hyponatremia (130-135 mmol/L)—even mild chronic hyponatremia increases fall risk 21% vs 5% and mortality 60-fold 2, 4

Monitoring Requirements

• Check serum sodium every 2 hours during initial correction for severe symptoms 1
• Check every 4-6 hours for mild-moderate symptoms 1
• Watch for signs of osmotic demyelination syndrome (dysarthria, dysphagia, oculomotor dysfunction, quadriparesis) typically occurring 2-7 days after rapid correction 1

Special Populations

• Cirrhotic patients: Require even more cautious correction (4-6 mmol/L per day maximum) due to higher risk of osmotic demyelination 1, 5
• Neurosurgical patients: Distinguish between SIADH (treat with fluid restriction) versus cerebral salt wasting (treat with volume and sodium replacement, NOT fluid restriction) 1
• Heart failure patients: Fluid restriction is first-line; vaptans may be considered for persistent severe hyponatremia despite fluid restriction 1, 5