Hyponatremia in Emergency Medicine Medication

Updated: Oct 18, 2022
  • Author: Kartik Shah, MD; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
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Medication Summary

Appropriate treatment of hyponatremia depends on the correct classification of hyponatremia, the concomitant disease state, the severity of symptoms, and the severity of hyponatremia.


Electrolyte Supplements

Class Summary

Hypertonic saline may be used to rapidly increase serum sodium level in patients with severe acute or chronic hyponatremia, as manifested by severe confusion, coma, seizures, or evidence of brainstem herniation.

Hypertonic (3%) saline

Contains 513 mEq/L of NaCl. Volume of hypertonic saline administered depends on current and desired serum sodium levels and patient's weight. In general, an increase of 4-6 mEq/L in serum sodium level is sufficient to arrest progression of symptoms in severe hyponatremia. Further rapid increase in serum sodium level not indicated.

Sodium bicarbonate

Commonly available ampoules are 8.4% sodium bicarbonate, with one 50-mL ampoule containing 50 mEq of Na. This can be used to raise serum Na in an emergent scenario where 3% hypertonic saline is not readily available, such as a hyponatremic seizure. For comparison, 100 mL of 3% hypertonic saline contains 51.3 mEq of NaCl.


Arginine Vasopressin Antagonists

Class Summary

These agents treat hyponatremia through V2 antagonism of AVP in the renal collecting ducts. This effect results in aquaresis (excretion of free water).

Conivaptan (Vaprisol)

Arginine vasopressin antagonist (V1A, V2) indicated for euvolemic (dilutional) and hypervolemic hyponatremia. Increases urine output of mostly free water, with little electrolyte loss.

Tolvaptan (Samsca)

Selective vasopressin V2 -receptor antagonist. Indicated for hypervolemic and euvolemic hyponatremia (ie, serum sodium level < 125 mEq/L) or less marked hyponatremia that is symptomatic and has resisted correction with fluid restriction. Used for hyponatremia associated with congestive heart failure, liver cirrhosis, and syndrome of inappropriate antidiuretic hormone secretion. Initiate or reinitiate in hospital environment only. Duration of use is limited to 30 days to minimize risk of liver injury.