Table 1 Biomarkers of muscle mass
Biomarker | Technique | Cut-off value |
|---|---|---|
Anthropometric measures | ||
Calf circumference (CC) | Measure the calf circumference at the greatest point (left leg for right handed subjects, and vice versa), while sitting, knee at ankle are at right angle and foot on the ground. Done with a non-elastic plastic tape. The measurement is taken on bare skin [25] | ˃ 31 cm is indicative of low muscle mass (recommended by WHO Expert Committee) [25] |
Mid-arm circumference (MAMC) | Measure the mid-arm circumference (non-dominant hand) with a non-elastic plastic tape, at the mid-point between the olecranon process and the acromion of the shoulder. The triceps skinfold thickness is measured using a calibrated skinfold caliper MAMC = mid-arm circumference–(3.14 × triceps skinfold thickness) [26] | Only one study determined cutoff values for sarcopenia ranging from 21.0 to 24.9 cm in men and 19.8 to 23.3 cm in women [26] |
Bioelectric impendence analysis (BIA) | Measurements are taken between the right wrist and ankle with the subject in a supine position Measurement of body composition compartments and calculation of the appendicular skeletal mass (ASM) [24] | Low muscle mass is considered when SMI less than 7 kg/m2 in men and 5.5 kg/m2 in women, according to the EWGSOP2 [7] |
Dual-energy X-ray absorptiometry (DXA) | Measurement of body composition compartments and calculation of the appendicular skeletal mass (ASM) [27] | |
Computed tomography (CT) | Calculate the CSA of: • The Abdominal muscle mass at the third or fourth or fourth lumbar vertebra • The psoas muscle | Muscular CSA must be adjusted for height to determine the SMI. (CSA/height2) - SMI cut-off values for men range from 52 to 55 cm2/m2 and 39 to 41 cm2/m2 for women [29] |
Ultrasonography (US) | Assess cross-sectional area, muscle thickness, echo intensity, fascicular length, contrast-enhanced vascularization, and elastography The anterior compartment of the thigh is an excellent anatomical location to take US measurements [27, 28] | No standard cut-off value |
Magnetic resonance imaging (MRI) | Provide information about muscular edema, fibrous substitution, and muscular elasticity and contraction [28] Magnetic resonance spectroscopy (MRS) analysis assesses muscle quality (intermuscular and intramyocellular lipid depots) [30] No standard imaging protocol | No standard cut-off value |
muscle-specific biomarkers • Procollagen type III N-terminal peptide (P3NP) • Peptides derived from the collagen type VI turnover • Skeletal muscle-specific isoform of troponin T • D3-creatine dilution method • Irisin • Cathepsin D | No standard cut-off value | |
Transforming growth factor (TGF) superfamily myostatin and growth differentiation factor-15 (GDF-15) | No standard cut-off value | |