Searchable abstracts of presentations at key conferences in endocrinology
Endocrine Abstracts (2013) 32 P864 | DOI: 10.1530/endoabs.32.P864

1Endocrinology Unit, Medical Department, Maggiore-Bellaria Hospital, Azienda Usl di Bologna, Bologna, Italy; 2Endocrinology Unit, Center for Research, Transfer and High Education on Chronic, Inflammatory, Degenerative and Neoplastic Disorders for the Development of Novel Therapies” (DENOThe), Department of Clinica, Florence, Italy; 3Division of Endocrinology and Metabolism, Georgetown University, Washington DC, USA; 4Sexual Medicine and Andrology Unit, University of Florence, Florence, Italy.


Introduction: Hyponatremia is the most common electrolyte disorder in clinical practice, and evidence to date indicates that severe hyponatremia is associated with increased morbidity and mortality. The aim of our study was to perform a comprehensive meta-analysis that included all the published studies that compared mortality rates in subjects with or without hyponatremia of any degree.

Methods: An extensive Medline, Embase, and Cochrane search was performed to retrieve all studies published up to October 1, 2012 using the words ‘hyponatremia’ and ‘mortality’.

Results: Eighty-one studies satisfied inclusion criteria encompassing a total of 850 222 patients, of whom 147 948 (17.4%) were hyponatremic. Across all 81 studies, hyponatremia was significantly associated with an increased risk of overall mortality (RR=2.60 (2.31–2.93)). Hyponatremia was also found to increase the risk of mortality in patients with multiple diseases, including myocardial infarction (RR=2.83 (2.23–3.58)), heart failure (RR=2.47 (2.09–2.92)), cirrhosis (RR=3.34 (1.91–5.83)), pulmonary infections (RR=2.49 (1.44–4.30)), mixed diseases (RR=2.50 (1.97–3.18)), and in hospitalized patients in whom the diagnosis was not specified (RR=2.48 (2.09–2.45)). A mean difference of serum (Na+) of 4.8 mmol/l was found in subjects who eventually died compared to survivors (130.1±5.6 vs 134.9±5.1 mmol/l, P<0.001). Furthermore, a meta-regression analysis showed that the hyponatremia-related risk of overall mortality was inversely correlated with serum (Na+) (S=−0.096 (−0.114, −0.077); I=13–710 (12.258–16.161); both P<0.0001). This association was confirmed in a multiple regression model after adjusting for age, sex, and associated morbidities such as diabetes mellitus.

Conclusions: This meta-analysis shows for the first time that even moderate serum (Na+) decreases are associated with an increased risk of mortality in commonly observed clinical conditions across large numbers of patients.

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