From the Guidelines
The initial approach to treating hyponatremia should prioritize correcting the underlying cause, with fluid restriction and hypertonic saline administration used judiciously based on the severity and type of hyponatremia, as evidenced by the most recent guidelines 1.
Key Considerations
- The severity of hyponatremia, onset, and underlying cause guide the treatment approach.
- For mild to moderate hyponatremia (sodium >120 mEq/L) without severe symptoms, fluid restriction to 800-1000 mL/day may be considered, particularly in cases of euvolemic or hypervolemic hyponatremia.
- Symptomatic or severe hyponatremia (sodium <120 mEq/L), especially with neurological symptoms, may require 3% hypertonic saline administration intravenously at a rate of 1-2 mL/kg/hour, with careful monitoring to avoid rapid correction.
- The correction rate should not exceed 8-10 mEq/L in the first 24 hours and 18 mEq/L in 48 hours to prevent osmotic demyelination syndrome, as recommended by recent guidelines 1.
Treatment by Type of Hyponatremia
- Hypovolemic hyponatremia: isotonic saline (0.9% NaCl) may be used to restore volume while correcting sodium levels.
- Hypervolemic hyponatremia: discontinuation of intravenous fluid therapy and free water restriction should be considered, with hypertonic sodium chloride administration reserved for severely symptomatic cases.
Monitoring and Adjustments
- Frequent monitoring of serum sodium levels (every 2-4 hours initially) is essential to guide therapy adjustments.
- Addressing the underlying cause is crucial, which may involve discontinuing offending medications, treating SIADH, managing heart failure, or correcting volume status, as highlighted in recent studies 1.
From the FDA Drug Label
Fluid restriction was to be avoided if possible during the first 24 hours of therapy to avoid overly rapid correction of serum sodium, and during the first 24 hours of therapy 87% of patients had no fluid restriction. The initial approach to treating hyponatremia includes avoiding fluid restriction during the first 24 hours of therapy to prevent overly rapid correction of serum sodium.
- Key considerations:
- Avoid fluid restriction in the first 24 hours
- Monitor serum sodium concentrations closely
- Titrate medication as needed to achieve normonatremia 2
From the Research
Initial Approach to Treating Hyponatremia
The initial approach to treating hyponatremia involves several key steps:
- Identifying the underlying cause of hyponatremia, such as certain medications, excessive alcohol consumption, very low-salt diets, or excessive free water intake during exercise 3
- Categorizing patients according to their fluid volume status (hypovolemic hyponatremia, euvolemic hyponatremia, or hypervolemic hyponatremia) 4, 3, 5
- Treating the underlying cause of hyponatremia, with treatment approaches varying depending on the patient's fluid volume status 4, 3, 5
Treatment Based on Fluid Volume Status
Treatment for hyponatremia is based on the patient's fluid volume status:
- Hypovolemic hyponatremia: treated with normal saline infusions 3
- Euvolemic hyponatremia: treated with restricting free water consumption or using salt tablets or intravenous vaptans 4, 3, 5
- Hypervolemic hyponatremia: treated primarily by managing the underlying cause (e.g., heart failure, cirrhosis) and free water restriction 4, 3, 5
Severe Symptomatic Hyponatremia
Severely symptomatic hyponatremia (with signs of somnolence, obtundation, coma, seizures, or cardiorespiratory distress) is a medical emergency:
- Treated with bolus hypertonic saline to reverse hyponatremic encephalopathy by increasing the serum sodium level by 4 mEq/L to 6 mEq/L within 1 to 2 hours, but by no more than 10 mEq/L within the first 24 hours 4, 3, 6
- Requires frequent biochemical monitoring and close monitoring to avoid overly rapid correction of sodium concentration, which can cause osmotic demyelination syndrome 3, 5, 6