Symptomatic patients with acute hyponatremia.
• Severe symptoms: 100 mL of 3% NaCl infused intravenously over 10 minutes × 3 as needed.
• Mild to moderate symptoms, in patients at low risk for herniation: 3% NaCl infused at 0.5-2 mL/kg/h.

To avoid osmotic demyelination syndrome (ODS) in patients with chronic hyponatremia (known duration > 48 hours), recommendations include the following:
• Minimum correction of serum sodium by 4-8 mmol/L per day, with a lower goal of 4-6 mmol/L per day if the risk for ODS is high.
• For patients at high risk for ODS: maximum correction of 8 mmol/L in any 24-hour period.
• For patients at normal risk for ODS: maximum correction of 10-12 mmol/L in any 24-hour period or 18 mmol/L in any 48-hour period
• For patients with syndrome of inappropriate ADH secretion, fluid restriction (with a goal of 500 mL/day below the 24-hour urine volume) is generally first-line therapy, but pharmacologic treatment (vaptans, urea, demeclocycline) should be considered if the patient's renal electrolyte-free water excretion is low or if the serum sodium concentration does not correct after 24-48 hours of fluid restriction.

Asymptomatic patients with hyponatremia.
• Hypovolemic hyponatremia: administration of isotonic saline to replace the contracted intravascular volume (thereby treating the cause of vasopressin release). Patients with hypovolemia secondary to diuretics may also need potassium repletion.
• Hypervolemic hyponatremia: restriction of salt and fluid, plus loop diuretics, and correction of the underlying condition.
• Normovolemic hyponatremia: restriction of free water restriction (< 1 L/day) is generally the treatment of choice. Base the volume of restriction on the patient's renal diluting capacity.

Acute hyponatremia (duration < 48 hours) can be safely corrected more quickly than chronic hyponatremia. A severely symptomatic patient with acute hyponatremia is at risk of brain edema.

See reference for more information.

Adapted from Medscape Drugs & Diseases. fast five quiz: hyponatremia essentials. Internet. Available at https://reference.medscape.com/viewarticle/919756?src=wnl_fastquiz_191026_mscpref&uac=6705FY&impID=2140669&faf=1 Accessed on January 25, 2020. To view the entire article and all other content on the Medscape News and Perspective site, a free, one-time registration is requi