[Relationship between serum uric acid levels and muscle strength/volume: a new insight from a large-scale survey]

Serum uric acid (UA) concentration is regulated by its production in the liver and/or intestine and its rate of excretion from the kidneys. However, little is known about skeletal muscle involvement in determining the physiological UA level. The present trial explores whether muscle strength and/or muscle volume is associated with UA levels.

Muscle strength was evaluated in terms of grasping power calculated as an average of right and left hand measurements in relation to other parameters in 14,333 subjects (median age; 41.2 years), who were recruited to the study. Skeletal muscle volume was calculated based on the bioimpedance method by subtracting estimated fat volume plus estimated bone weight from the total body weight.

1) Multiple regression analyses to explain the association with UA levels (dependent variable) revealed that BMI, BUN, triglyceride, muscle strength, AST, age and sex are independent variables. 2) Higher UA levels (assessed as 4 UA quartiles) are associated with higher muscle volume, muscle strength, BMI, DBP, and serum creatinine (Cr) concentration. 3) Greater DBP (assessed as 2 UA categories) was associated with higher BMI, muscle strength, muscle volume, UA levels and serum Cr concentration. 4) Regression coefficient "t" for muscle strength was the largest among the other parameters including serum Cr concentration in the UA level ranging from 5.5 to 6.5 mg/dL.

There was an association between muscle strength/volume and UA levels in the near physiological UA range, suggesting that the circulating UA levels can be, at least in part, controlled by its production in the skeletal muscles.