What is the dosing frequency for Sodium Chloride (NaCl) tablets in treating hyponatremia?

Sodium Chloride Tablet Dosing for Hyponatremia

For mild to moderate symptomatic hyponatremia or asymptomatic SIADH not responding to fluid restriction, administer sodium chloride 100 mEq orally three times daily (total 300 mEq/day), combined with fluid restriction to 1 L/day. 1, 2

Dosing Based on Symptom Severity

Severe Symptomatic Hyponatremia

• Do not use oral sodium tablets - severe symptoms (seizures, coma, altered mental status) require immediate 3% hypertonic saline intravenously with target correction of 6 mmol/L over 6 hours or until symptoms resolve 1, 2
• Total correction must not exceed 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome 1, 2

Mild to Moderate Symptoms or Asymptomatic

• Sodium chloride 100 mEq orally three times daily (administered every 8 hours) 1, 2
• Combine with fluid restriction to 1 L/day 1, 2
• Add high protein diet to augment solute intake 2
• Monitor serum sodium every 4-6 hours initially, then daily once stable 2

FDA-Approved Oral Formulation

The FDA-approved sodium chloride oral solution 23.4% provides:

• Serving size: 4 mL (equivalent to 936 mg sodium chloride) 3
• This delivers 368 mg elemental sodium (16 mEq) per 4 mL dose 3
• For ages 9-50 years: 4 mL per dose as directed by physician 3

Important calculation: To achieve 100 mEq per dose, you would need approximately 25 mL of the 23.4% solution (since 4 mL = 16 mEq, therefore 100 mEq ÷ 16 mEq × 4 mL ≈ 25 mL) 3

Etiology-Specific Dosing

SIADH (Euvolemic Hyponatremia)

• First-line: Fluid restriction to 1 L/day 1, 2
• If no response after 24-48 hours: Add NaCl 100 mEq orally three times daily 1, 2
• Nearly half of SIADH patients do not respond to fluid restriction alone 4

Cerebral Salt Wasting

• Primary treatment is volume repletion with normal saline intravenously 1, 2
• Oral sodium supplementation can be added as adjunct therapy 2
• Never use fluid restriction - this worsens outcomes 1

Hypervolemic Hyponatremia (Cirrhosis, Heart Failure)

• Fluid restriction to 1-1.5 L/day is primary treatment 1, 2
• Oral sodium tablets are generally not recommended as they may worsen fluid overload 1
• Focus on treating underlying condition 1

Critical Safety Parameters

Maximum Correction Rates

• Standard patients: 4-8 mmol/L per day, maximum 8 mmol/L in 24 hours 1, 2
• High-risk patients (liver disease, alcoholism, malnutrition): 4-6 mmol/L per day 1, 2
• Never exceed 1 mmol/L per hour for chronic hyponatremia 1

Monitoring Requirements

• Check serum sodium every 4-6 hours during initial correction 2
• Calculate sodium deficit: Desired increase (mEq/L) × (0.5 × ideal body weight in kg) 1, 2
• Monitor for hyperkalemia, especially with renal impairment 2
• Watch for signs of osmotic demyelination syndrome (dysarthria, dysphagia, oculomotor dysfunction) typically 2-7 days after rapid correction 1

Common Pitfalls to Avoid

• Home preparation of salt tablets is not recommended due to potential formulation errors 1
• Ignoring mild hyponatremia (130-135 mmol/L) - even mild cases increase fall risk and mortality 1
• Using oral tablets for severe symptomatic hyponatremia - these patients require IV hypertonic saline 1, 2
• Failing to combine oral sodium with fluid restriction in SIADH - both interventions are necessary 1, 2
• Overcorrection beyond 8 mmol/L in 24 hours risks osmotic demyelination syndrome 1, 2

Alternative to Oral Tablets

Hourly oral sodium chloride can provide predictable correction for selected patients unable to receive IV therapy: calculate dose to deliver equivalent of 0.5 mL/kg/hour of 3% NaCl, administered hourly with frequent sodium monitoring 5