What is the management approach for hyponatremia (low sodium levels) in clinical practice?

Hyponatremia Management - Simplified Approach for MD Medicine JR3

Initial Assessment & Classification

Start by determining volume status and symptom severity - this drives your entire management strategy. 1

Step 1: Check Serum Sodium Level & Symptoms

• Mild: 130-135 mmol/L 1
• Moderate: 120-125 mmol/L 1
• Severe: <120 mmol/L 1

Severe symptoms (medical emergency): Seizures, coma, altered mental status, cardiorespiratory distress 2 Mild symptoms: Nausea, vomiting, weakness, headache, confusion 3

Step 2: Assess Volume Status (Clinical Examination)

• Hypovolemic: Orthostatic hypotension, dry mucous membranes, decreased skin turgor, tachycardia 1
• Euvolemic: No edema, normal BP, normal skin turgor, moist mucous membranes 1
• Hypervolemic: Peripheral edema, ascites, JVD, pulmonary congestion 1

Step 3: Order Essential Labs

• Serum osmolality, urine osmolality 1
• Urine sodium concentration 1
• Serum creatinine, urea 1
• Thyroid function (TSH), cortisol if indicated 1

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Treatment Algorithm

FOR SEVERE SYMPTOMATIC HYPONATREMIA (Emergency)

Administer 3% hypertonic saline immediately - do not wait for complete workup. 1

Dosing: 100 mL bolus over 10 minutes, can repeat up to 3 times at 10-minute intervals 1 Target: Increase sodium by 6 mmol/L over first 6 hours OR until symptoms resolve 1 Critical limit: NEVER exceed 8 mmol/L correction in 24 hours 1

Monitoring:

• Check sodium every 2 hours during initial correction 1
• Once symptoms resolve, check every 4 hours 1
• ICU admission recommended 1

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FOR HYPOVOLEMIC HYPONATREMIA

Give isotonic saline (0.9% NaCl) for volume repletion. 1

Management steps:

1. Discontinue diuretics immediately 1
2. Start normal saline infusion 1
3. Correct at maximum 8 mmol/L per 24 hours 1
4. Once euvolemic, reassess and adjust management 1

Urine sodium <30 mmol/L confirms hypovolemia 1

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FOR EUVOLEMIC HYPONATREMIA (SIADH)

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

Step-by-step approach:

1. First-line: Restrict fluids to 1000 mL/day 1
2. If no response: Add oral sodium chloride 100 mEq three times daily 1
3. For resistant cases: Consider vaptans (tolvaptan 15 mg once daily) 1, 4

Alternative options for SIADH:

• Urea (effective but poor palatability) 2
• Demeclocycline 1
• Loop diuretics 1

Common causes to address: Medications (SSRIs, carbamazepine), lung pathology, CNS disorders, malignancy 5

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FOR HYPERVOLEMIC HYPONATREMIA (Heart Failure/Cirrhosis)

Fluid restriction to 1-1.5 L/day for sodium <125 mmol/L. 1

Management protocol:

1. Fluid restriction: 1000-1500 mL/day 1
2. Temporarily stop diuretics if sodium <125 mmol/L 1
3. For cirrhosis: Add albumin infusion (6-8 g per liter of ascites drained) 1
4. Avoid hypertonic saline unless life-threatening symptoms 1

For resistant cases: Consider tolvaptan 15 mg once daily, but use with extreme caution in cirrhosis (10% GI bleeding risk vs 2% placebo) 4

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Critical Correction Rate Guidelines

THE GOLDEN RULE: Maximum 8 mmol/L in 24 hours 1

High-risk patients (require slower correction at 4-6 mmol/L/day): 1

• Advanced liver disease
• Alcoholism
• Malnutrition
• Prior encephalopathy
• Severe hyponatremia (<120 mmol/L)

If Overcorrection Occurs:

1. Immediately stop current fluids 1
2. Switch to D5W (5% dextrose in water) 1
3. Consider desmopressin to slow/reverse rapid rise 1
4. Target: Bring total 24-hour correction to ≤8 mmol/L 1

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Special Situations

Neurosurgical Patients (SAH, Brain Injury)

Distinguish Cerebral Salt Wasting (CSW) from SIADH - treatment is opposite! 1

CSW characteristics:

• True hypovolemia with high urine sodium (>20 mmol/L) 1
• Hypotension, tachycardia 1
• Treatment: Volume + sodium replacement with normal saline or 3% saline 1
• Add: Fludrocortisone 0.1-0.2 mg/day 1
• NEVER restrict fluids - worsens outcomes 1

SIADH in neurosurgical patients:

• Euvolemic with high urine sodium 1
• Treatment: Fluid restriction 1

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Common Pitfalls to Avoid

1. Ignoring mild hyponatremia (130-135 mmol/L) - increases fall risk (21% vs 5%) and mortality (60-fold increase if <130 mmol/L) 1

2. Using normal saline in SIADH - worsens hyponatremia 1

3. Using fluid restriction in CSW - catastrophic outcomes 1

4. Correcting too rapidly - causes osmotic demyelination syndrome (dysarthria, dysphagia, quadriparesis 2-7 days later) 1

5. Using hypertonic saline in hypervolemic hyponatremia without life-threatening symptoms - worsens edema/ascites 1

6. Inadequate monitoring during correction - check sodium frequently 1

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Practical Calculation

Sodium deficit formula: 1 Desired increase in Na (mEq/L) × (0.5 × ideal body weight in kg)

Example: For 60 kg patient wanting 6 mEq/L increase: 6 × (0.5 × 60) = 180 mEq sodium needed

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Quick Reference for Indian Practice

For asymptomatic/mild cases:

• Hypovolemic → Normal saline 1
• Euvolemic (SIADH) → Fluid restriction 1 L/day 1
• Hypervolemic → Fluid restriction 1-1.5 L/day + treat underlying cause 1

For severe symptomatic cases:

• 3% saline boluses regardless of volume status 1
• Target 6 mmol/L in 6 hours 1
• Maximum 8 mmol/L in 24 hours 1
• ICU monitoring 1

Tolvaptan use (if available): Start 15 mg once daily for euvolemic/hypervolemic hyponatremia resistant to fluid restriction, but avoid in cirrhosis due to bleeding risk 4