Development of severe hyponatraemia in hospitalized patients: treatment-related risk factors and inadequate management

Nephrol Dial Transplant. 2006 Jan;21(1):70-6. doi: 10.1093/ndt/gfi082. Epub 2005 Sep 2.


Background: Although hyponatraemia [plasma sodium (PNa)<136 mmol/l] frequently develops in hospital, risk factors for hospital-acquired hyponatraemia remain unclear.

Methods: Patients who presented with severe hyponatraemia (PNa<or=125 mmol/l) were compared with patients with hospital-acquired severe hyponatraemia in a 3 month hospital-wide cohort study.

Results: Thirty-eight patients had severe hyponatraemia on admission (PNa 121+/-4 mmol/l), whereas 36 patients had hospital-acquired severe hyponatraemia (PNa 133+/-5-->122+/-4 mmol/l). In hospital-acquired hyponatraemia, treatment started significantly later (1.0+/-2.6 vs 9.8+/-10.6 days, P<0.001) and the duration of hospitalization was longer (18.2+/-11.5 vs 30.7+/-23.4 days, P=0.01). The correction of PNa in hospital-acquired hyponatraemia was slower after both 24 h (6+/-4 vs 4+/-4 mmol/l, P=0.009) and 48 h (10+/-6 mmol/l vs 6+/-5 mmol/l, P=0.001) of treatment. Nineteen patients (26%) from both groups were not treated for hyponatraemia and this was associated with a higher mortality rate (seven out of 19 vs seven out of 55, P=0.04). Factors that contributed to hospital-acquired hyponatraemia included: thiazide diuretics (none out of 38 vs eight out of 36, P=0.002), drugs stimulating antidiuretic hormone (two out of 38 vs eight out of 36, P=0.04), surgery (none out of 38 vs 10 out of 36, P<0.001) and hypotonic intravenous fluids (one out of 38 vs eight out of 36, P=0.01). Symptomatic hyponatraemia was present in 27 patients (36%), and 14 patients died (19%).

Conclusions: The development of severe hyponatraemia in hospitalized patients was associated with treatment-related factors and inadequate management. Early recognition of risk factors and expedited therapy may make hospital-acquired severe hyponatraemia more preventable.

Publication types

  • Comparative Study

MeSH terms

  • Adult
  • Age Distribution
  • Aged
  • Aged, 80 and over
  • Cohort Studies
  • Female
  • Hospitalization*
  • Hospitals, University
  • Humans
  • Hyponatremia / epidemiology*
  • Hyponatremia / etiology*
  • Hyponatremia / physiopathology
  • Iatrogenic Disease*
  • Incidence
  • Male
  • Middle Aged
  • Netherlands / epidemiology
  • Risk Assessment
  • Severity of Illness Index
  • Sex Distribution
  • Sodium Chloride Symporter Inhibitors / adverse effects*
  • Survival Rate


  • Sodium Chloride Symporter Inhibitors