Mild Chronic Hyponatremia Is Associated With Falls, Unsteadiness, and Attention Deficits

The study objective was to determine the eventual consequences (falls, unsteadiness, and cognitive impairment) of mild chronic hyponatremia, which is generally considered as asymptomatic. In a case-control study, we focused on the incidence of falls among 122 patients (mean age 72 ± 13 years) with asymptomatic chronic hyponatremia (mean serum sodium concentration [SNa] 126 ± 5 mEq/L), who were admitted to the medical emergency department, compared with 244 matched controls. To explore the mechanisms of the excess of falls, we prospectively asked 16 comparable patients (mean age 63 ± 15 years; SNa ± 2 mEq/L) to perform 8 attention tests and a gait test consisting of 3 steps “in tandem,” in which we measured the “total traveled way” by the center of pressure or total traveled way. Thereafter, the patients were treated and tested again (50% of the patients were tested first with normal SNa to avoid learning biases). Epidemiology of falls: Twenty-six patients (21.3%) of 122 were admitted for falls, compared with only 5.3% of the control patients (adjusted odds ratio: 67; 95% confidence: 7.5-607; P