Low relative skeletal muscle mass indicative of sarcopenia is associated with elevations in serum uric acid levels: Findings from NHANES III

Background  Sarcopenia may be related to increases in reactive oxygen species formation and inflammation, both of which are associated with elevations in serum uric acid. Objective  To test the hypothesis that a reduced skeletal muscle mass index, indicative of sarcopenia, is related to elevations in uric acid. Design  Cross-sectional analysis of nationally representative data. Setting  Third National Health and Nutrition Examination Survey, 1988–1994. Patients  7544 men and women 40 years of age and older who had uric acid, skeletal muscle mass, and select covariate information. Measurements  Skeletal muscle mass assessment was based on a previously published equation including height, BIA-resistance, gender, and age. Absolute skeletal muscle mass was calculated for all study population individuals and compared against the sex-specific mean for younger adults. Serum uric acid data were gathered from the NHANES laboratory file. Results  A logistic regression analysis revealed that elevations in serum uric acid are significantly related to sarcopenia status. For every unit (mg/dL) increase in uric acid, the odds ratio of manifesting a skeletal muscle mass index at least one standard deviation below the reference mean was 1.12. Participants in the highest grouping (>8 mg/dL) of serum uric acid concentration had 2.0 times the odds of manifesting sarcopenia compared to the lowest grouping (<6 mg/dL) (p<0.01) after adjusting for the additional covariates. Limitations  This study design was limited in its cross-sectional nature. Potential selection, measurement, and recall bias may have occurred, and methodology used to classify sarcopenia status based on skeletal muscle mass index is not validated. Conclusion  This observation provides support for the theory that elevations in uric acid may lead to sarcopenia, although the proposed mechanism needs further experimental support.