Elsevier

Mayo Clinic Proceedings

Volume 90, Issue 10, October 2015, Pages 1348-1355
Mayo Clinic Proceedings

Original article
Sodium Correction Practice and Clinical Outcomes in Profound Hyponatremia

https://doi.org/10.1016/j.mayocp.2015.07.014Get rights and content

Abstract

Objectives

To assess the epidemiology of nonoptimal hyponatremia correction and to identify associated morbidity and in-hospital mortality.

Patients and Methods

An electronic medical record search identified all patients admitted with profound hyponatremia (sodium <120 mmol/L) from January 1, 2008, through December 31, 2012. Patients were classified as having optimally or nonoptimally corrected hyponatremia at 24 hours after admission. Optimal correction was defined as sodium correction in 24 hours of 6 through 10 mmol/L. We investigated the association between sodium correction and demographic and outcome variables, including occurrence of osmotic demyelination syndrome (ODS). Baseline characteristics by correction outcome categories were compared using the Kruskal-Wallis test for continuous variables and the χ2 test for categorical variables. Odds ratios for in-hospital mortality between groups were assessed using logistic regression. Adjusted differences in hospital length of stay (LOS) and intensive care unit (ICU) LOS were assessed using the Dunnett 2-tailed t test.

Results

A total of 412 patients satisfied inclusion criteria of whom 174 (42.2%) were admitted to the ICU. A total of 211 (51.2%) had optimal correction of their hyponatremia at 24 hours, 87 (21.1%) had undercorrected hyponatremia, and 114 (27.9%) had overcorrected hyponatremia. Both patient factors and treatment factors were associated with nonoptimal correction. There was a single case of ODS. Overcorrection was not associated with in-hospital mortality or ICU LOS. When adjusted for patient factors, undercorrection of profound hyponatremia was associated with an increase in hospital LOS (9.3 days; 95% CI, 1.9-16.7 days).

Conclusion

Nonoptimal correction of profound hyponatremia is common. Fortunately, nonoptimal correction is associated with serious morbidity only infrequently.

Section snippets

Study Design and Setting

Our study was a retrospective analysis of our longstanding electronic medical record (EMR) system at the Rochester campus of Mayo Clinic. The local institutional review board reviewed and approved the project. We performed a search of the EMR to identify all patients admitted to our institution from January 1, 2008, through December 31, 2012, with a serum sodium level less than 120 mmol/L after correction for serum glucose using a well-described correction factor.15 We excluded patients younger

Results

The Figure shows how patients were identified for inclusion in the study, as well as their subsequent grouping according to degree of sodium correction at 24 hours. A total of 412 patients were included; 211 patients (51.2%) had optimally corrected hyponatremia at 24 hours, 87 patients (21.1%) had undercorrected hyponatremia, and 114 (27.7%) had overcorrected hyponatremia according to our predefined criteria. The closest sodium measurements to the 24-hour mark (used to estimate Na24) were a

Discussion

Our results indicate that nonoptimal correction of hyponatremia was very common in patients admitted with profound hyponatremia, occurring in nearly half of the patients in this cohort. Although it was frequent, overcorrection was associated with only a single case of ODS (corresponding to an incidence of approximately 1% in those who were overcorrected) and was not associated with changes in hospital mortality or LOS. Hospital LOS was increased in patients who met our definition of

Conclusion

In the current study, we identified a high rate of nonoptimal sodium correction during the first 24 hours of treatment in a large unselected cohort of patients admitted to our institution with profound hyponatremia during a 5-five year period. Fortunately, this high rate of nonoptimal correction was not associated with increased in-hospital mortality and seemed to be associated with morbidity only infrequently—ODS occurred in only a single patient, corresponding to an incidence of approximately

Acknowledgments

The authors gratefully acknowledge the entire Multidisciplinary Epidemiology and Translational Research in Intensive Care research group for their support, which made this project possible. The authors also thank Mayo Clinic's Center for Translational Science Activities for their support. The contents of this publication are solely the responsibility of the authors and do not necessarily represent the official views of the National Institutes of Health.

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    For editorial comment, see page 1320

    Grant Support: The work was supported by the Mayo Clinic's Center for Translational Science Activities grant UL1 TR000135 from the National Center for Advancing Translational Sciences.

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