Fluid and Electrolytes

HYPONATREMIA   DEFINITION Hyponatremia = Serum Na⁺ < 135 mEq/L Most common electrolyte abnormality in ICU Severity classification Severity Serum Na⁺ Mild 130–134 Moderate 125–129 Severe <125  PATHOPHYSIOLOGY   Hyponatremia is fundamentally a disorder of water balance, NOT sodium deficit Excess ADH (vasopressin) → water retention → dilution of Na⁺ ADH PHYSIOLOGY Released from posterior pituitary Stimuli: […]