title: Ultrasound-Based Detection of Low Muscle Mass for Diagnosis of Sarcopenia in Older Adults.
abstract: To establish muscle-specific cut-off values for ultrasound-based detection of low muscle mass, and to assess its prevalence in a population of frail older subjects when applying the cut-points of different muscles and those of different sarcopenic indices.
  
  
  
  Cross-sectional study.
  
  
  
  Geriatric outpatient clinic and clinical research laboratory.
  
  
  
  A total of 44 older adults (30 women and 14 men, mean age 82 years, range 67-93 years) and 60 younger individuals (30 women and 30 men, mean age 26 years, range 20-36 years) participated. Body composition and thickness of 4 lower limb muscles (rectus femoris, vastus lateralis, tibialis anterior, medial gastrocnemius) were respectively assessed by bioelectrical impedance analysis (BIA) and ultrasonography.
  
  
  
  Site-specific cut-points for ultrasound-based assessment of low muscle mass (muscle thickness values 2 standard deviations below the gender-specific means of our sample of younger subjects) and comparative prevalence rates of low muscle mass.
  
  
  
  The following site-specific cut-points for muscle thickness were identified: rectus femoris: 20 mm in men and 16 mm in women; vastus lateralis: 17 mm in men and 15 mm in women; tibialis anterior: 23 mm in men and 22 mm in women; and medial gastrocnemius: 13 mm in both men and women. The prevalence of low muscle mass in older adults was highly dependent on the muscle being investigated; it varied from 86% for thigh muscles to 30% for leg muscles. Moreover, the prevalence of low muscle mass was highly dependent on the applied diagnostic criterion and on the adopted cut-off value; it ranged from 2% to 75% for different BIA-derived criteria.
  
  
  
  We suggest that muscle ultrasonography provides physiatrists with a practical and accurate tool for identifying individuals with low muscle mass. However, the usability of cut-off values established in our group of healthy younger subjects of white ethnicity to identify low muscle mass in older individuals of different ethnic groups remains to be demonstrated in future studies.
authors.affiliation: Division of Physical Medicine and Rehabilitation, Department of Surgical Sciences, and Division of Endocrinology, Diabetology and Metabolism, Department of Medical Sciences, University of Turin, Turin, Italy(∗). Electronic address: marco.minetto@unito.it.
authors.forename: Marco A
authors.initials: MA
authors.lastname: Minetto
authors.affiliation: Division of Endocrinology, Diabetology and Metabolism, Department of Medical Sciences, University of Turin, Turin, Italy; Biolab, Department of Electronics and Telecommunications, Politecnico di Torino, Turin, Italy(†).
authors.forename: Cristina
authors.initials: C
authors.lastname: Caresio
authors.affiliation: Division of Endocrinology, Diabetology and Metabolism, Department of Medical Sciences, University of Turin, Turin, Italy(‡).
authors.forename: Tommaso
authors.initials: T
authors.lastname: Menapace
authors.affiliation: Division of Endocrinology, Diabetology and Metabolism, Department of Medical Sciences, University of Turin, Turin, Italy(§).
authors.forename: Arnel
authors.initials: A
authors.lastname: Hajdarevic
authors.affiliation: Division of Endocrinology, Diabetology and Metabolism, Department of Medical Sciences, University of Turin, Turin, Italy(‖).
authors.forename: Andrea
authors.initials: A
authors.lastname: Marchini
authors.affiliation: Biolab, Department of Electronics and Telecommunications, Politecnico di Torino, Turin, Italy(¶).
authors.forename: Filippo
authors.initials: F
authors.lastname: Molinari
authors.affiliation: Neuromuscular Research Laboratory, Schulthess Clinic, Zurich, Switzerland(#).
authors.forename: Nicola A
authors.initials: NA
authors.lastname: Maffiuletti
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001823:Body Composition; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal; D015995:Prevalence; D055948:Sarcopenia