How is hyponatremia evaluated and managed in the emergency department (ED)?

Updated: Aug 24, 2020
  • Author: Kartik Shah, MD; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
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The ED evaluation of patients with hyponatremia includes determining the cause and the chronicity of the hyponatremic state in order to direct appropriate therapy. [24]

Acute hyponatremia is less common than chronic hyponatremia and typically is seen in patients with a history of sudden free water loading (eg, patients with psychogenic polydipsia, infants fed tap water or inappropriately diluted formula for 1-2 d, patients given hypotonic fluids in the postoperative period, a marathon runner drinking water without electrolyte supplementation).

Acute evolution of hyponatremia leaves little opportunity for compensatory extrusion of CNS intracellular solutes.

The ultimate danger for these patients is brainstem herniation when sodium levels fall below 120 mEq/L.

The therapeutic goal is to increase the serum sodium level rapidly by 4-6 mEq/L over the first 1-2 hours.

The source of free water must be identified and eliminated.

In patients with healthy renal function and mild to moderately severe symptoms, the serum sodium level may correct spontaneously without further intervention.

Patients with seizures, severe confusion, coma, or signs of brainstem herniation should receive hypertonic (3%) saline to rapidly correct the serum sodium level toward normal, but only enough to arrest the progression of symptoms. An increase in serum sodium level of 4-6 mEq/L is generally sufficient. Any further correction is potentially dangerous and must be avoided unless necessary to correct continued seizures or other severe CNS abnormality. If hypertonic saline is not available, 8.4% sodium bicarbonate can be considered as an alternative for emergent sodium correction.

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