Osmotic stress and mortality in elderly patients with kidney failure: a retrospective study

Abstract

Purpose

Water balance disorders are associated with a high risk of death in elderly patients. The role of osmotic stress intensity and its direction toward hypo- or hypernatremia is a matter of controversy regarding patients’ survival. The aims of this study were, first, to measure the frequency of cellular hydration disorders in patients over 75 years old hospitalized in nephrology department for reversible acute renal failure, and second, to compare the impact of hyperhydration and hypohydration on the risk of death at 6 months.

Patients and methods

We retrospectively studied the data of 279 patients with chronic kidney disease (CKD), aged 75 years or older, with pre-renal azotemia who experienced dysnatremia. We classified them according to natremia levels and compared their outcome in univariate and multivariate analysis.

Results

The patients were on average 83.2±5.4 years old. Among them, 128 were normonatremic, 82 were hyponatremic and 69 were hypernatremic. Osmotic stress intensity appreciated by the variation rate of natremia did not differ significantly between hyper- and hyponatremic patients. Patients had CKD stage 3B and 4 with acute kidney injury (AKI) of different severities. We observed that only hypernatremia was linked to death in the first 6 months following hospital discharge.

Conclusion

Hypernatremia is a strong predictor of fatal outcome in elderly patients suffering from chronic kidney impairment and referred for pre-renal azotemia.

Keywords:

• acute kidney injury
• aging
• chronic kidney failure
• hypernatremia
• osmoregulation

Acknowledgments

The authors thank Dr Sonia Doi for reviewing the manuscript and helpful comments. The abstract of this paper was presented at the 18th Annual Meeting of French Society of Pharmacology and Therapeutics, April 22–24, 2014, Poitiers, France, as a poster presentation/conference talk with interim findings. The poster’s abstract was published in “Discussed Poster Abstracts” in Fundamental and Clinical Pharmacology, Volume 28, Issue s1, May 2014: DOI:10.1111/fcp.12065. There was no sponsor involved in this study.

Author contributions

CG-C contributed to analysis and interpretation of biostatistical data and preparation of the manuscript. MD contributed to selection of subjects and data collection. VLME provided comments for the design of the study and contributed to manuscript preparation. GF contributed to concept and design of the study, analysis and interpretation of data and critical revision of the manuscript. All authors contributed to data analysis, drafting or revising the article, gave final approval of the version to be published, and agree to be accountable for all aspects of the work.

Disclosure

The authors report no conflicts of interest in this work.