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.