Notably, the diagnostic performances of our combined models, and especially that of the efficient and clinically practical four‐biomarker panel (Combined Model 2), exceeded the diagnostic performance of all currently reported single biomarkers or biomarker panels for sarcopenia, including proteomic markers MMP9/TIMP1 [22] and RBP [23], and metabolic markers such as Cr/CysC [24, 25], AST/ALT [26] and Irisin [27]. The gene discussed is MMP9; the disease is sarcopenia.