QJM Advance Access originally published online on May 13, 2008
QJM 2008 101(7):583-588; doi:10.1093/qjmed/hcn061
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Mild hyponatremia and risk of fracture in the ambulatory elderly
From the 1Department of General Internal Medecine, Hopital Erasme, Université Libre de Bruxelles, and 2Department of Intensive Care Hopital Erasme and European Centre for Advanced Research in Economics and Statistics (ECARES), Université Libre de Bruxelles, Bruxelles, Belgique
Address correspondence to F. Gankam Kengne, Service de Médecine Interne Générale, Hôpital Erasme, 808, Route de Lennik, 1070 Bruxelles, Belgium. email: fgankamk{at}ulb.ac.be
Received 30 January 2008 and in revised form 4 April 2008
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Abstract |
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Background: Mild hyponatremia is the commonest electrolyte imbalance in the older population and has been shown to be associated with gait and attention deficits resulting in higher frequency of falls. The association of mild hyponatremia and bone fracture is still unknown.
Objective: To determine if mild hyponatremia is associated with increased risk of bone fracture in ambulatory elderly.
Design, setting and participants: Case control study of 513 cases of bone fracture after incidental fall in ambulatory patients aged 65 or more in general university hospital. Controls were age and sex matched randomly selected ambulatory patients without history of bone fracture.
Main exposure measures: Odds ratio (OR) of bone fracture after incidental fall associated with presence of hyponatremia.
Results: Prevalence of hyponatremia (serum sodium <135 mEq/l,) in patients with bone fracture and in controls patient was, respectively, 13.06% and 3.90%. Hyponatremia was mild and asymptomatic in all patients (mean serum sodium 131 mEq/l) and was found to be associated with bone fracture after incidental fall in ambulatory elderly (unadjusted OR: 3.47, 95% CI: 2.09–5.79, and adjusted OR: 4.16 95% CI: 2.24–7.71). Hyponatremia was either drug induced (36% diuretics, 17% selective serotonin reuptake inhibitors) or resulted from idiopathic syndrome of inappropriate antidiuretic hormone secretion (37%). Hyponatremia was associated with 9.20% of all bone fractures.
Conclusions: Mild asymptomatic hyponatremia is associated with bone fracture in ambulatory elderly and avoiding iatrogenic hyponatremia or treating hyponatremia may decrease the number of bone fractures in this population.