Gender-specific association between urinary sodium excretion and body composition: Analysis of the 2008-2010 Korean National Health and Nutrition Examination Surveys.

Objective: Few studies have reported the relationship between sarcopenia and the estimated amount of sodium excreted in 24 h, as measured by the spot urine test (E24UNA), in a community-dwelling cohort. We investigated the gender specific association between E24UNA values and body composition indices.

Materials And Methods: Data from a total of 7162 participants (3545 men and 3617 postmenopausal women) aged 45 years or older were obtained from multiple Korea National Health and Nutrition Examination Surveys (2008-2010) and analyzed. The total amount of sodium excreted in the urine in a 24-h period was estimated with spot urine specimens. Sarcopenia was defined as an appendicular skeletal muscle mass divided by body weight (ASM/Wt) that was less than 1 standard deviation below the sex-specific mean for young adults.

Results: E24UNA values were positively correlated with body mass index, waist circumference, total fat mass, and blood pressure; in contrast, E24UNA values were negatively correlated with ASM/Wt in both sexes. Compared with those in the lowest E24UNA tertile, participants in the highest E24UNA tertile were at higher risk for sarcopenia (men: odds ratio (OR)=1.3 [95% confidence interval (CI)=1.07-1.59]; women: OR=1.41 [95% CI=1.16-1.73]). Further classification of subjects with sarcopenia into sarcopenic obese and sarcopenic nonobese groups revealed that the highest E24UNA values were found in the sarcopenic obese group; this difference was statistically significant. The next highest levels were found in the sarcopenic nonobese group, followed by the nonsarcopenic group. This trend was observed in both sexes.

Conclusion: High E24UNA values were independently associated with both sarcopenia and obesity in Korean individuals older than 45 years. These results suggest that high salt intake may have a deleterious effect on body composition.