肌少症的定義由單純的肌肉量減少，經由許多共識會議，逐漸進展到肌肉量、肌力及生理功能的綜合評估，理想的評估工具需考量準確性、安全性、可近性、成本等，目前以雙能量X射線吸收儀(dual energy x-ray absorptiometry’ DXA)或生物電阻抗分析(bioelectrical impedance analysis’ BIA)評估肌肉量、以握力評估肌力及以行走速度評估生理功能為主，但切點仍有人種、地區上的不同，定義及切點確立之後，將有助於臨床上有效的篩檢出肌少症的高危險群，做進一步的預防與介入。肌少症與許多不良預後相關，包括失能、罹病率及死亡率增加等，近期的研究逐漸開始探討肌少症與其他老年症候群(例如：認知障礙、憂鬱、及跌倒)的關聯，但目前台灣的研究以橫斷性研究為主，未來仍需更多縱貫性的研究，了解肌少症可能帶來的不良預後。

Yi-Chun Chou1,2, Hao-Hsiang Chang2, Ding-Cheng Chan1,3 Abstract: The original definition of sarcopenia was loss of skeletal muscle mass. Through many consensus conferences’ the definition gradually evolved to loss of muscle mass plus deficiencies in muscle strength or physical performance. An ideal assessment tools should take accuracy’ safety’ accessibility’ and costs into consideration. Currently’ the main assessments include dual energy x-ray absorptiometry (DXA) and/or bioelectrical impedance analysis (BIA) for muscle mass’ grip strength for muscle strength and gait speed as an indicator for physical performance. However’ there is still geographical difference of the cut-off values for each indicator. It is of paramount importance to establish national or regional criteria of sarcopenia to target high risk groups for prevention and intervention. Sarcopenia is associated with many adverse outcomes’ including disability’ morbidity and mortality. Recent research has gradually explored the relationship between sarcopenia and other geriatric syndromes (e.g.’ cognitive impairment’ depression’ and fall). However’ the studies in Taiwan were mainly of cross-sectional design. Future longitudinal studies on the associations of sarcopenia and adverse outcomes are needed.