Estimation of Muscle Mass Using Creatinine/Cystatin C Ratio in Japanese Community-Dwelling Older People

Sarcopenia is defined as a combination of low skeletal muscle mass index (SMI), weak muscle strength, and reduced physical function. Recently, many studies have reported that the creatinine/cystatin C ratio (Cr/CysC) is useful for evaluating muscle mass. We designed a cross-sectional study with separate model development and validation groups to develop a prediction equation to estimate bioimpedance analysis (BIA)-measured SMI with Cr/CysC.