| The sarcopenia index (SI) has gradually gained attention in various fields in recent years. Initially, research on SI focused on muscle mass and sarcopenia. Currently, it has recently expanded to nutrition, disease prognosis, and other directions. However, the association between SI and muscle mass, sarcopenia, and nutritional prognosis remains controversial. This article reviews the development, physiological mechanism, and applications in sarcopenia diagnosis, and applications in other fields of SI in the four aspects. The aim is to gain a systematic understanding of the research status of SI and to analyze that SI serves as an adjunct diagnostic indicator for sarcopenia or muscle mass. However, whether it may become a substitute diagnostic marker for sarcopenia requires further validation through more high-quality and reproducible research. |