Trunk muscle quality and quantity are associated with renal volume in nondiabetic people

BACKGROUND: Renal disease is a major problem in terms of community health and the economy. Skeletal muscle is involved in crosstalk with the kidney. We therefore investigated the relationship between muscle quality and quantity, and renal parenchymal volume (RPV). METHODS: The association between the parameters of skeletal muscle and RPV/body surface area (BSA) was analyzed by computed tomography in 728 middle-aged participants without kidney disease or diabetes mellitus in a cross-sectional study. A retrospective cohort study of 68 participants was undertaken to analyze the association between changes in RPV/BSA and muscle parameters. Parameter change was calculated as follows: parameter at the follow-up examination/parameter at the baseline examination. The normal attenuation muscle (NAM) and low attenuation muscle (LAM) were identified by Hounsfield Unit thresholds of +30 to +150, and –29 to +29, respectively. RESULTS: Positive correlations were found between estimated glomerular filtration rate and RPV/BSA (r = 0.451, P < .0001). Multiple regression analyses revealed that the NAM index was positively related to RPV/BSA (β = 0.458, P < .0001), whereas the LAM index was negatively related to RPV/BSA (β = –0.237, P < .0001). In this cohort study, a change in the LAM index was independently associated with a change in RPV/BSA (β = –0.349, P = .0032). CONCLUSION: Both trunk muscle quantity and quality were associated with renal volume related to renal function in nondiabetic people. An increase in low quality muscle volume might be related to a decrease in renal volume.