Comparative Measures of Lean Body Tissues in the Clinical Setting

Age-related decreases in muscle mass and function, known as sarcopenia, have been shown to be related to functional limitation, frailty, and an increase in morbidity and mortality. While the most accurate method to assess muscle mass is biopsy, this is impractical clinically. There are numerous methods to assess skeletal muscle mass including dual-energy X-ray absorptiometry (DEXA) and bioelectrical impedance analysis (BIA) which are low cost and accessible. There are also more specific standards for assessing muscle mass or cross-sectional muscle area including magnetic resonance imaging (MRI) and computerized tomography (CT). Each method has its own advantages and limitations in clinical practice. Other emerging methods include peripheral quantitative CT and ultrasound. The ideal test would be valid and reliable, low cost, and practical combined with simple measurements of isometric strength to define sarcopenia and predict future health events.