How are hyponatremia treatment decisions and recommendations made?

Updated: Jun 17, 2019
  • Author: Eric E Simon, MD; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Answer

The recommendations for treatment of hyponatremia rely on the current understanding of CNS adaptation to an altered serum osmolality. In the setting of an acute drop in the serum osmolality, neuronal cell swelling occurs due to the water shift from the extracellular space to the intracellular space (ie, Starling forces). Swelling of the brain cells elicits the following two osmoregulatory responses:

  • It inhibits both arginine vasopressin secretion from neurons in the hypothalamus and hypothalamic thirst center. This leads to excess water elimination as dilute urine.

  • There is an immediate cellular adaptation with loss of electrolytes, and over the next few days, there is a more gradual loss of organic intracellular osmolytes. [4]

Therefore, correction of hyponatremia must take into account the chronicity of the condition. Acute hyponatremia (duration < 48 h) can be safely corrected more quickly than chronic hyponatremia. Correction of serum sodium that is too rapid can precipitate severe neurologic complications. Most individuals who present for diagnosis, versus individuals who develop it while in an inpatient setting, have had hyponatremia for some time, so the condition is chronic, and correction should proceed accordingly.


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