What is the dosage of sodium chloride (NaCl) for treating hyponatremia?

From the Guidelines

For the treatment of hyponatremia, the dosage of sodium chloride (NaCl) should be tailored to the severity of the condition, with 3% hypertonic saline reserved for severe symptomatic cases and 0.9% normal saline for milder cases, aiming for a correction rate not to exceed 8 mEq/L per 24-hour period to prevent osmotic demyelination syndrome, as recommended by the American Association for the Study of Liver Diseases in 2021 1.

Treatment Approach

The approach to treating hyponatremia involves assessing the severity of the condition and the presence of symptoms.

• For severe hyponatremia (<120 mEq/L), especially with symptoms, 3% hypertonic saline is recommended for short-term treatment.
• The goal is to correct serum sodium levels at a rate of 4-6 mEq/L per 24-hour period, not exceeding 8 mEq/L per 24-hour period, to minimize the risk of osmotic demyelination syndrome (ODS) 1.
• For patients with cirrhosis and hyponatremia, the management strategy may include water restriction and, in some cases, the use of vasopressin receptor antagonists for a short term, but the primary focus for acute correction, especially in severe cases, remains the judicious use of hypertonic saline 1.

Administration Guidelines

• For severe symptomatic hyponatremia, 3% hypertonic saline can be administered at a dose of 100-150 mL over 10-20 minutes, potentially repeated if symptoms persist, under close monitoring 1.
• The use of 0.9% normal saline may be considered for less severe cases or for maintenance, with the dose adjusted based on the patient's volume status and the severity of hyponatremia.
• Oral salt tablets may be an option for mild cases, with doses ranging from 3-9 grams daily, divided into multiple doses, but this approach is less commonly recommended for acute management.

Monitoring and Adjustment

• Frequent monitoring of serum sodium levels, ideally every 2-4 hours initially, is crucial to adjust the therapy and prevent overcorrection or undercorrection.
• The underlying cause of hyponatremia must be addressed concurrently, as sodium supplementation alone may not be sufficient to resolve the condition if there are ongoing losses or inappropriate ADH secretion 1.

From the FDA Drug Label

WARNINGS: ... Sodium Chloride Injection, USP, 23.4% is hypertonic and must be diluted prior to administration. The FDA drug label does not answer the question.

From the Research

Dosage of Sodium Chloride for Treating Hyponatremia

• The dosage of sodium chloride (NaCl) for treating hyponatremia depends on the severity and persistence of the symptoms, as well as the patient's fluid volume status 2, 3.
• For severely symptomatic hyponatremia, a bolus of 3% NaCl can be administered, with a goal of increasing the serum sodium level by 4-6 mEq/L within 1-2 hours 3, 4.
• The optimal dose of 3% NaCl bolus therapy is still under debate, with studies comparing the efficacy and safety of 100 mL vs 250 mL boluses 4.
• A study found that a 250 mL bolus of 3% NaCl was more effective than a 100 mL bolus in increasing serum sodium levels, without increasing the risk of overcorrection 4.
• For asymptomatic mild hyponatremia, an adequate solute intake with an initial fluid restriction of 500 mL/day can be preferred, with adjustments based on serum sodium levels 2.
• Hourly oral NaCl tablets can be an alternative to intravenous 3% NaCl for selected patients with severe hyponatremia, with careful monitoring of serum sodium concentration 5.
• The preferred therapy for hyponatremic encephalopathy is a 100-ml bolus of 3% sodium chloride administered in repeated doses until symptoms reverse, with the goal of increasing the serum sodium 5-6 mEq/L 6.