Impact of hypernatremia, hyponatremia and their comparison on ICU mortality

Introduction

Serum sodium homeostasis is important in the critically ill patient [1–3]. We studied the effect of hypernatremia, hyponatremia and their comparison on ICU mortality in our patient population.

Methods

We studied 274 patients hospitalized in a general ICU of a major teaching hospital in Tehran, Iran, cross-sectionally, between 2004 and 2006. Patients' biographical data, reasons for admission, hyponatremia (sodium less than 135 mEq/l) and hypernatremia (sodium more than 145 mEq/l) during the ICU stay were recorded and their effects on mortality were assessed.

Results

The mortalities of patients with hyponatremia (34.33% versus 15.37% with OR = 5.69 and 95% CI from 2.87 to 11.30) and with hypernatremia (55.17% versus 17.78% with OR = 2.80 and 95% CI from 1.43 to 5.49) were significantly higher than patients without it. The mean age of patients with sodium imbalance was higher compared with those without it (hypo-natremia and hypernatremia 52.25 ± 21.12 vs. 44.40 ± 20.28 years and 55.59 ± 19.69 vs. 48.52 ± 21.83 years, respectively). Mortality was significantly higher in hypernatremic compared with hyponatremic patients (55.2% vs. 34.3%, respectively, 95% CI from 7.7% to 33.9%; P = 0.0034).

Conclusion

Serum sodium imbalances carry unacceptably high mortality [4]. Patients with hypernatremia showed higher ICU mortality as compared with those with hyponatremia.