UMEM Educational Pearls

Acute Hyponatremia and the Critically Ill

  • I just left a busy ED shift during which we had a patient with altered mental status and a serum Na of 115 mmol/L.
  • Recall that severe hyponatremia may present with lethargy, disorientation, agitation, nausea/vomiting, altered mental status, abnormal respirations, and seizures.
  • For severe, symptomatic hyponatremia, the treatment of choice is 3% hypertonic saline
  • At a rate of 100 ml/hr, the serum Na should rise approximately 2 mmol/L per hour.
  • In general, the duration of treatment with hypertonic saline is based upon sign and sypmtom improvement.
  • For those with more longstanding hyponatremia, serum Na should not be increased by more than 12 mmol in the first 24 hours.


Schrier RW, Bansal S. Diagnosis and management of hyponatremia in acute illness. Curr Opin Crit Care 2008;14:627-34.