How is hyponatremia treated?

Treatment of Hyponatremia

Treatment of hyponatremia should be tailored to the underlying cause, volume status, severity of symptoms, and chronicity of the condition, with careful attention to correction rates to avoid osmotic demyelination syndrome. 1

Assessment and Classification

Before initiating treatment, proper assessment is essential:

1. Volume status assessment:

   • Hypovolemic: Orthostatic hypotension, dry mucous membranes, urine Na <20 mEq/L
   • Euvolemic: Normal vital signs, no edema, urine Na >20-40 mEq/L
   • Hypervolemic: Edema, ascites, elevated JVP, urine Na <20 mEq/L 2

2. Severity classification:

   • Mild: 126-135 mEq/L
   • Moderate: 120-125 mEq/L
   • Severe: <120 mEq/L 1, 2

3. Chronicity assessment:

   • Acute: <48 hours
   • Chronic: >48 hours 1

Treatment Algorithm Based on Volume Status and Symptoms

1. Hypovolemic Hyponatremia

• Treatment: Discontinue diuretics/laxatives and provide fluid resuscitation
• Fluids of choice: 5% IV albumin or crystalloid (preferentially lactated Ringer's) 1
• Monitoring: Serum sodium every 2-4 hours initially during active correction 2

2. Euvolemic Hyponatremia (SIADH)

For mild symptoms or asymptomatic:

• First-line: Fluid restriction to 1-1.5 L/day 2
• If inadequate response:
  • Salt tablets (NaCl 100 mEq PO TID)
  • High protein diet 1
  • Consider tolvaptan (starting dose 15 mg once daily, can increase to 30 mg after 24 hours, maximum 60 mg daily) for short-term treatment (≤30 days) 2, 3

For severe symptoms (seizures, coma, altered mental status):

• Treatment: 3% hypertonic saline 1, 4
• Goal: Increase serum sodium by 4-6 mEq/L within 1-2 hours until symptoms resolve 2, 4
• Administration: 100-150 mL bolus or continuous infusion 5
• Maximum correction: 8 mEq/L in 24 hours 1, 2

3. Hypervolemic Hyponatremia (Cirrhosis, Heart Failure)

• First-line: Fluid restriction to 1,000 mL/day for moderate hyponatremia (120-125 mEq/L) 1
• For severe hyponatremia (<120 mEq/L): More severe fluid restriction plus albumin infusion 1
• For cirrhotic patients with ascites:
  • Start with aldosterone antagonist (spironolactone 100 mg/day)
  • Add furosemide for recurrent ascites 2
  • Consider tolvaptan for short-term use, but be aware of increased risk of gastrointestinal bleeding 2, 3

Correction Rate Guidelines

• Standard correction rate: Maximum 8 mEq/L in 24 hours 1, 2
• High-risk patients (alcoholism, malnutrition, hypokalemia, liver disease): Limit to 4-6 mEq/L per day 2
• Acute symptomatic hyponatremia: Can be corrected more rapidly (1 mEq/L/hour) until symptoms resolve 1, 6
• Chronic hyponatremia: Slower correction to avoid osmotic demyelination syndrome 1, 6

Monitoring During Treatment

• Serum sodium: Every 2-4 hours initially during active correction 2
• Volume status: Regular assessment through vital signs, intake/output, and weight 2
• For tolvaptan: Monitor for changes in serum electrolytes and volume 2, 3

Complications to Avoid

Osmotic Demyelination Syndrome (ODS)

• Risk factors: Advanced liver disease, alcoholism, severe hyponatremia, malnutrition, metabolic derangements 1
• Prevention: Adhere to correction rate limits
• Signs: Dysarthria, dysphagia, oculomotor dysfunction, quadriparesis 1
• If overcorrection occurs: Consider relowering with electrolyte-free water or desmopressin 1, 5

Special Considerations for Cirrhotic Patients

• Hyponatremia in cirrhosis increases risk of hepatic encephalopathy, hepatorenal syndrome, and spontaneous bacterial peritonitis 2
• Avoid hypertonic saline in decompensated cirrhosis as it may worsen ascites and edema 2
• Albumin infusion has been associated with improvement in hyponatremia in hospitalized cirrhotic patients 1

Clinical Impact of Hyponatremia

Even mild hyponatremia is associated with:

• Cognitive impairment
• Gait disturbances
• Increased rates of falls and fractures
• Increased hospital stay and mortality 4

By following this structured approach to hyponatremia management, clinicians can effectively treat this common electrolyte disorder while minimizing the risk of complications.