What is the management of hyponatremia (low sodium levels)?

From the Guidelines

Hyponatremia management should prioritize the correction rate to prevent osmotic demyelination syndrome, with a recommended increase of up to 5 mmol/L in the first hour and a limit of 8–10 mmol/L every 24 hours thereafter, as suggested by the most recent guidelines 1. The management of hyponatremia depends on the severity, symptoms, and underlying cause, and it is crucial to address the underlying cause to ensure long-term management.

• For mild to moderate asymptomatic hyponatremia (sodium >125 mEq/L), fluid restriction to 800-1000 mL/day is the primary approach, along with treating the underlying cause.
• For symptomatic or severe hyponatremia (<125 mEq/L), more aggressive intervention is needed, and in patients with severe symptoms like seizures or altered consciousness, 3% hypertonic saline should be administered at 100-150 mL over 10-20 minutes, which can be repeated 2-3 times if symptoms persist. 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.
• For SIADH-related hyponatremia, fluid restriction plus oral salt tablets may be used, or medications like tolvaptan (starting at 15 mg daily) or demeclocycline (300-600 mg twice daily) can be considered, but it is essential to monitor patients closely due to the risk of hepatotoxicity associated with tolvaptan 1. Loop diuretics like furosemide (20-40 mg IV or oral) may help in volume-overloaded states, and frequent monitoring of serum sodium (every 2-4 hours initially in severe cases) is essential to ensure appropriate correction rates. It is also crucial to discontinue medications that contribute to hyponatremia, such as thiazide diuretics, SSRIs, or certain antiepileptics, when appropriate, and to consider the specific management approach for patients with cirrhosis and ascites, as outlined in recent practice guidance by the American Association for the Study of Liver Diseases 1.

From the FDA Drug Label

Removal of excess free body water increases serum osmolality and serum sodium concentrations. All patients treated with tolvaptan, especially those whose serum sodium levels become normal, should continue to be monitored to ensure serum sodium remains within normal limits If hypernatremia is observed, management may include dose decreases or interruption of tolvaptan treatment, combined with modification of free-water intake or infusion.

Hyponatremia management with tolvaptan involves monitoring serum sodium levels to prevent hypernatremia. If hypernatremia occurs, management includes:

• Dose decreases or interruption of tolvaptan treatment
• Modification of free-water intake or infusion It is essential to monitor serum sodium levels closely, especially in patients whose serum sodium levels become normal, to ensure they remain within normal limits 2.

From the Research

Hyponatremia Management

• Hyponatremia is defined by a serum sodium level of less than 135 mEq/L and most commonly results from water retention 3.
• Symptoms and signs of hyponatremia range from mild and nonspecific (such as weakness or nausea) to severe and life-threatening (such as seizures or coma) 3.
• The approach to managing hyponatremia should consist of treating the underlying cause, and patients should be categorized according to their fluid volume status (hypovolemic hyponatremia, euvolemic hyponatremia, or hypervolemic hyponatremia) 3, 4.

Treatment Options

• Urea and vaptans can be effective treatments for the syndrome of inappropriate antidiuresis and hyponatremia in patients with heart failure, but have adverse effects 3.
• Hypertonic saline is reserved for patients with severely symptomatic hyponatremia, and US and European guidelines recommend treating severely symptomatic hyponatremia with bolus hypertonic saline to reverse hyponatremic encephalopathy 3, 4.
• Tolvaptan can be effective in correcting hyponatremia, but carries a significant risk of overly rapid sodium correction, especially in patients with starting sodium <125 mmol/l 5, 6.
• A very low dose of tolvaptan (7.5 mg) may be effective in correcting hyponatremia with less risk of overcorrection compared to a 15 mg dose 7.

Important Considerations

• Overly rapid correction of chronic hyponatremia may cause osmotic demyelination, a rare but severe neurological condition 3, 4.
• Baseline serum sodium and urea nitrogen concentrations can predict the rapidity of hyponatremia correction following tolvaptan use in SIADH 5.
• Close electrolyte monitoring is necessary when using tolvaptan to avoid overly rapid sodium correction 6.