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Prognostic consequences of borderline dysnatremia: pay attention to minimal serum sodium change

Michael Darmon1*, Eric Diconne1, Bertrand Souweine2, Stéphane Ruckly34, Christophe Adrie5, Elie Azoulay6, Christophe Clec'h7, Maïté Garrouste-Orgeas8, Carole Schwebel4, Dany Goldgran-Toledano9, Hatem Khallel10, Anne-Sylvie Dumenil11, Samir Jamali12, Christine Cheval13, Bernard Allaouchiche14, Fabrice Zeni1 and Jean-François Timsit34

Author Affiliations

1 Medical ICU, Saint-Etienne University Hospital, Avenue Albert Raymond, 42270, Saint-Priest-en-Jarez, France; Jacques Lisfranc Faculty of Medicine, Jean Monnet University, 15 Rue Ambroise Paré, 42023, Saint-Etienne, France

2 Medical ICU, Gabriel Montpied University Hospital, 58 Rue Montalembert, 63003, Clermont-Ferrand Cedex 1, France

3 University of Grenoble 1 (Joseph Fourier) Integrated Research Center U 823 - Albert Bonniot Institute, Grenoble University Hospital, Rond Point de la Chantourne, 38706, La Tronche, Grenoble, France

4 Polyvalent ICU, Grenoble University Hospital, Pavillon Dauphine, BP217, 38043, Grenoble Cedex 9, France

5 Department of Physiology, Cochin University Hospital, APHP, 27 Rue du Faubourg St Jacques, 75014, Paris, France

6 Medical ICU, St Louis University Hospital, 1 Avenue Claude Vellefaux, 75010, Paris, France

7 Medical-Surgical ICU, Avicenne University Hospital, 125 Rue de Stalingrad, 93000, Bobigny, France; Paris-13 University, 93000, Bobigny, France

8 Polyvalent ICU, Groupe Hospitalier St Joseph, 145 Rue Raymond Losserand, 75014, Paris, France

9 Polyvalent ICU, Gonesse General Hospital, 25 Rue Bernard Fevrier, 95500, Gonesse, France

10 Intensive Care Unit, Centre Hospitalier Andrée Rosemon, Avenue des Flamboyants, 97306, Cayenne, France

11 Surgical ICU, Antoine Béclère University Hospital, 157 Rue de la Porte de Trivaux, 92141, Clamart Cedex, France

12 Polyvalent ICU, Centre Hospitalier Sud Essonne Dourdan-Etampes-Siège, 26 Avenue Charles de Gaulle, 91150, Etampes, France

13 Medical-Surgical ICU, Hyeres Hospital, Rue du Maréchal Juin, 83407, Hyeres, France

14 Surgical ICU, Edouard Herriot University Hospital, Hospices Civiles de Lyon, 5 Place Arsonval, 69437, Lyon, France

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Critical Care 2013, 17:R12  doi:10.1186/cc11937

See related commentary by Menon et al.,

Published: 21 January 2013



To assess the prevalence of dysnatremia, including borderline changes in serum sodium concentration, and to estimate the impact of these dysnatremia on mortality after adjustment for confounders.


Observational study on a prospective database fed by 13 intensive care units (ICUs). Unselected patients with ICU stay longer than 48 h were enrolled over a 14-year period were included in this study. Mild to severe hyponatremia were defined as serum sodium concentration < 135, < 130, and < 125 mmol/L respectively. Mild to severe hypernatremia were defined as serum sodium concentration > 145, > 150, and > 155 mmol/L respectively. Borderline hyponatremia and hypernatremia were defined as serum sodium concentration between 135 and 137 mmol/L or 143 and 145 respectively.


A total of 11,125 patients were included in this study. Among these patients, 3,047 (27.4%) had mild to severe hyponatremia at ICU admission, 2,258 (20.3%) had borderline hyponatremia at ICU admission, 1,078 (9.7%) had borderline hypernatremia and 877 (7.9%) had mild to severe hypernatremia. After adjustment for confounder, both moderate and severe hyponatremia (subdistribution hazard ratio (sHR) 1.82, 95% CI 1.002 to 1.395 and 1.27, 95% CI 1.01 to 1.60 respectively) were associated with day-30 mortality. Similarly, mild, moderate and severe hypernatremia (sHR 1.34, 95% CI 1.14 to 1.57; 1.51, 95% CI 1.15 to 1.99; and 2.64, 95% CI 2.00 to 3.81 respectively) were independently associated with day-30 mortality.


One-third of critically ill patients had a mild to moderate dysnatremia at ICU admission. Dysnatremia, including mild changes in serum sodium concentration, is an independent risk factor for hospital mortality and should not be neglected.