What are the steps for treating hyponatremia (low sodium levels in the blood)?

Step-by-Step Treatment of Hyponatremia

The treatment of hyponatremia should follow a systematic approach based on symptom severity, volume status, and rate of development, with careful attention to correction rates to prevent osmotic demyelination syndrome. 1

Step 1: Assess Severity and Symptoms

• Classify hyponatremia by severity:

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

• Evaluate for symptoms:

  • Mild symptoms: Nausea, vomiting, headache, weakness
  • Severe symptoms: Mental status changes, seizures, coma 2, 3

Step 2: Determine Volume Status

• Assess volume status through clinical examination and laboratory tests:

Volume Status	Urine Osmolality	Urine Sodium	Clinical Signs	Likely Diagnosis
Hypovolemic	Variable	<20 mEq/L	Orthostatic hypotension, dry mucous membranes	Volume depletion
Euvolemic	>500 mOsm/kg	>20-40 mEq/L	No edema, normal vital signs	SIADH
Hypervolemic	Elevated	<20 mEq/L	Edema, ascites, elevated JVP	Heart failure, cirrhosis

• Consider central venous pressure (CVP) measurement:
  • CVP <5 cm H₂O suggests hypovolemia
  • CVP 6-10 cm H₂O suggests euvolemia 2

Step 3: Treatment Based on Symptom Severity

For Severe Symptomatic Hyponatremia (seizures, coma):

1. Administer 3% hypertonic saline:

   • Give as 100-150 mL bolus or continuous infusion 5
   • Target correction: 4-6 mEq/L within 1-2 hours or until severe symptoms improve 1, 3
   • Maximum correction: 8 mEq/L in first 24 hours 2
   • Formula for sodium deficit: Desired increase in Na (mEq/L) × (0.5 × ideal body weight) 2

2. Monitor sodium levels:

   • Every 2 hours initially during active correction 1
   • Transfer to ICU for close monitoring 2
   • Track fluid intake/output and daily weight 2

For Mild to Moderate Symptomatic Hyponatremia:

• Treatment depends on volume status:

Hypovolemic Hyponatremia:

1. Administer isotonic saline (0.9% NaCl) 6
2. Discontinue diuretics/laxatives if applicable 1
3. Consider 5% albumin for specific conditions 1

Euvolemic Hyponatremia (SIADH):

1. Fluid restriction (500-1000 mL/day) 1, 2
2. Add salt tablets (100 mEq TID) if no response 2
3. Consider high protein diet 2
4. For resistant cases:
   • Consider urea (40g every 8 hours) 2
   • Consider tolvaptan starting at 15 mg once daily (for short-term use ≤30 days) 1, 7

Hypervolemic Hyponatremia:

1. Fluid restriction to 1000 mL/day 1
2. Treat underlying condition (heart failure, cirrhosis) 1, 6
3. Consider albumin infusion for severe cases 1

Step 4: Monitor Correction Rate

• Safe correction limits:

  • Standard patients: Maximum 10-12 mEq/L in 24 hours 1, 8
  • High-risk patients (alcoholism, malnutrition, liver disease): Maximum 4-6 mEq/L in 24 hours 1

• If correction is occurring too rapidly:

  • Consider administering desmopressin 1
  • Provide hypotonic fluids 5

Special Considerations

For Cerebral Salt Wasting (CSW):

• Avoid fluid restriction - can increase risk of cerebral infarction 2
• Administer normal saline with salt supplementation 2
• Consider fludrocortisone (mineralocorticoid) - shown to reduce negative sodium balance in SAH patients 2

For Chronic Hyponatremia:

• Correct slowly at 0.5 mEq/L/hour to prevent osmotic demyelination syndrome 4
• Asymptomatic patients: Fluid restriction and close monitoring are often sufficient 4

Pitfalls to Avoid

1. Misdiagnosing volume status - physical examination alone has low sensitivity (41.1%) for determining ECF status 2

2. Fluid restricting CSW patients - can lead to cerebral infarction (21 of 26 fluid-restricted SAH patients developed infarction in one study) 2

3. Overly rapid correction - can cause irreversible neurological complications including osmotic demyelination syndrome 4, 1

4. Inadequate monitoring - sodium levels should be checked frequently during correction 1

5. Treating laboratory values rather than patients - focus on symptom improvement rather than achieving normal sodium levels 5