Treatment of hyponatremic encephalopathy with a 3% sodium chloride protocol: a case series

Am J Kidney Dis. 2015 Mar;65(3):435-42. doi: 10.1053/j.ajkd.2014.09.021. Epub 2014 Nov 25.


Background: 3% sodium chloride solution is the accepted treatment for hyponatremic encephalopathy, but evidence-based guidelines for its use are lacking.

Study design: A case series.

Setting & participants: Adult patients presenting to the emergency department of a university hospital with hyponatremic encephalopathy, defined as serum sodium level < 130 mEq/L with neurologic symptoms of increased intracranial pressure without other apparent cause, and treated with a continuous infusion of 500mL of 3% sodium chloride solution over 6 hours through a peripheral vein.

Predictors: Hyponatremic encephalopathy defined as serum sodium level < 130 mEq/L with neurologic symptoms of increased intracranial pressure without other apparent cause.

Outcomes: Change in serum sodium level within 48 hours, improvement in neurologic symptoms, and clinical evidence of cerebral demyelination, permanent neurologic injury, or death within 6 months' posttreatment follow-up.

Results: There were 71 episodes of hyponatremic encephalopathy in 64 individuals. Comorbid conditions were present in 86% of individuals. Baseline mean serum sodium level was 114.1±0.8 (SEM) mEq/L and increased to 117.9±1.3, 121.2±1.2, 123.9±1.0, and 128.3±0.8 mEq/L at 3, 12, 24, and 48 hours following the initiation of 3% sodium chloride solution treatment, respectively. There was a marked improvement in central nervous system symptoms within hours of therapy in 69 of 71 (97%) episodes. There were 12 deaths, all of which occurred following the resolution of hyponatremic encephalopathy and were related to comorbid conditions, with 75% of deaths related to sepsis. No patient developed neurologic symptoms consistent with cerebral demyelination at any point during the 6-month follow-up period.

Limitations: Lack of a comparison group and follow-up neuroimaging studies. Number of cases is too small to provide definitive assessment of the safety of this protocol.

Conclusions: 3% sodium chloride solution was effective in reversing the symptoms of hyponatremic encephalopathy in the emergency department without producing neurologic injury related to cerebral demyelination on long-term follow-up in this case series.

Keywords: 3% sodium chloride; Hyponatremia; cerebral demyelination; electrolyte abnormality; hypertonic saline; hyponatremic encephalopathy; neurologic injury; sodium.

MeSH terms

  • Aged
  • Brain Edema / blood
  • Brain Edema / diagnosis*
  • Brain Edema / drug therapy*
  • Cohort Studies
  • Female
  • Humans
  • Hyponatremia / blood
  • Hyponatremia / diagnosis*
  • Hyponatremia / drug therapy*
  • Male
  • Middle Aged
  • Prospective Studies
  • Saline Solution, Hypertonic / administration & dosage*
  • Saline Solution, Hypertonic / chemistry
  • Treatment Outcome


  • Saline Solution, Hypertonic