Yanishi M, et al. - Researchers investigated whether serum creatinine and cystatin C levels could offer an effective assessment of muscle mass—an important step in detecting sarcopenia—in kidney transplant recipients. They evaluated 62 patients who had kidney transplantation at Kansai Medical University Hospital, and used dual-energy X-ray absorptiometry to determine muscle mass. Using immunoassay, they measured serum creatinine and cystatin C levels. In the male and female groups, the skeletal muscle index was found to be remarkably and positively correlated to creatinine/cystatin C ratio. Findings suggested that, in kidney transplant recipients, creatinine/cystatin C ratio may be an appropriate tool to evaluate muscle mass.