What is the dose of hypertonic (3% sodium chloride) saline for severe hyponatremia?

From the Guidelines

For severe hyponatremia, the recommended dose of 3% hypertonic saline is not explicitly stated in terms of volume, but the goal is to raise serum sodium by up to 5 mmol/L in the first hour and limit the increase to 8-10 mmol/L every 24 hours thereafter, as recommended by the guidelines on the management of ascites in cirrhosis 1.

Key Considerations

• The use of hypertonic saline should be reserved for patients with severely symptomatic acute hyponatremia, especially if a transplant is imminent, as stated in the guidelines on the management of ascites in cirrhosis 1.
• The correction of serum sodium should be done slowly to prevent central pontine myelinolysis, 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 recommended by the guidelines on the management of ascites in cirrhosis 1.
• Patients should be monitored for signs of volume overload, and treatment should occur in an ICU setting with close neurological monitoring, as the use of hypertonic saline may worsen fluid overload, as noted in the guidelines on the management of ascites in cirrhosis 1.

Additional Guidance

• The American Association for the Study of Liver Diseases recommends that the use of hypertonic saline be reserved for short-term treatment of patients with symptomatic or severe hyponatremia or those with imminent liver transplant, as stated in the 2021 practice guidance on the diagnosis, evaluation, and management of ascites, spontaneous bacterial peritonitis, and hepatorenal syndrome 1.
• The goal rate of increase of serum sodium is 4-6 mEq/L per 24-hour period, not to exceed 8 mEq/L per 24-hour period, to ameliorate the risk of osmotic demyelination syndrome, as recommended by the American Association for the Study of Liver Diseases 1.

From the Research

Dose of Hypertonic Saline for Severe Hyponatremia

The dose of hypertonic (3% sodium chloride) saline for severe hyponatremia can be estimated based on the patient's body weight and the desired rate of increase in sodium levels.

• The initial infusion rate (ml/kg per hour) can be calculated by multiplying the body weight (kg) by the desired rate of increase in sodium (mmol/L per hour) 2.
• The goal is to increase the serum sodium by 1-2 mmol/L per hour until symptoms abate, or a total magnitude of correction of 12 mmol/L in 24 hours or 18 mmol/L in 48 hours is achieved 2.
• Studies have shown that rapid correction of severe hyponatremia with intravenous hypertonic saline solution can be effective in improving outcomes 3, 4.
• However, it is essential to avoid overly rapid correction of hyponatremia, as this can result in serious neurologic injury 2, 5.
• A slow and sustained correction of sodium levels can be achieved with concomitant use of 3% hypertonic saline and other medications, such as DDAVP 6.

Key Considerations

• The treatment of severe hyponatremia should be guided by the presence or absence of significant neurologic signs and symptoms 2.
• The rate of correction of serum sodium concentration should be no more than 0.5 mM per liter per hour in chronic symptomatic hyponatremia 5.
• Severe symptomatic acute hyponatremia should be treated promptly and rapidly using hypertonic saline to initially reach a mildly hyponatremic level 5.