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

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