Episodic Hyponatremia is Associated with Increased Mortality in Hemodialysis Patients

Abstract

Introduction: Hyponatremia is common in many patient populations and has been linked to increased mortality. Hyponatremia in hemodialysis (HD) patients is also common, yet, only cross-sectional analyses are available. The hypothesis of the current study was that not only persistent, but also episodic hyponatremia in HD patients is associated with increased mortality.

Methods: The prevalence of persistent and episodic (short duration (<3 months), high frequency (>=8 episodes) and long duration (>3 months), low (1-3 episodes) and medium (4-7 episodes) frequency) patterns of hyponatremia (plasma Na < 135 mmol/L) was investigated in 2473 patients on in-center HD, using plasma Na levels determined monthly over a median of 4.6 years. Both persistent and episodic hyponatremia are linked to mortality.

Results: Normal sodium over the entire observations period was observed in 34% of patients, episodic short duration, high frequency in 9% of patients and long duration, low and medium frequency in 8% of patients. Both persistent hyponatremia and long duration, low/medium frequency were associated with decrease survival compared to patients without hyponatremia.

Conclusion: Our results suggest that episodic hyponatremia may be just as an important predictor of mortality as stable hyponatremia.  This result further implies that a cross sectional analysis of hyponatremic patients undergoing hemodialysis may underestimate the risk associated with hyponatremia due to the potential for its episodic nature.

*Indicates faculty mentor