Hyponatremia

Treatment

Acute (<48 hours), symptomatic (weakness, lethargy, coma, seizures, etc.)

• Most common causes of acute hyponatremia:
  • Acute psychogenic polydipsia
  • MDMA
  • Hypotonic fluid administration (including repletion during surgery or by endurance athletes)
• Goal is to rapidly correct sodium using 3% normal saline
  • 1-2 mL/kg/hr

Acute (<48 hours), asymptomatic

• Goal is to correct sodium at a steady rate, can raise it more quickly than chronic hyponatremia (if positive the hyponatremia is acute), as the brain has not had time to adapt
• Can use 3% normal saline or more conservative strategies listed below based on the severity of the hyponatremia

Chronic (>48 hours), symptomatic

• Goal is to rapidly correct sodium using 3% saline

Chronic (>48 hours), asymptomatic (weakness, lethargy, coma, seizures, etc.)

• Goal is to raise serum sodium 6-8 mEq/L/24 hours
• Hypovolemic hyponatremia: Give isotonic saline
• Euvolemic hyponatremia: Restrict fluids
• Hypervolemic hyponatremia: Restrict fluids and sodium, diurese (NOT with thiazide diuretics, as these medications can cause/exacerbate hyponatremia)
• Rapid overcorrection of hyponatremia may lead to Osmotic Demyelination Syndrome (ODS, formerly Central Pontine Myelinolysis)
  • If correcting too rapidly, can have the patient drink 500 mL of water, D5W can be administered, or desmopressin (DDAVP) can be administered to re-lower the serum sodium level