However, results are conflicting and effects of sarcopenia and other nonrenal factors on serum creatinine are not adjusted in BIS and FAS equations (33); for this reason, cystatin C (CysC), which is known to be less affected by muscle turnover than serum creatinine (34), is emerging as a biomarker to estimate renal function in the older with sarcopenia and frailty (35–37). This evidence concerns the gene CST3 and sarcopenia.