title: Circulating irisin levels as a predictive biomarker for sarcopenia: A cross-sectional community-based study.
abstract: OBJECTIVE
  Myokines are peptides released by the skeletal muscle, and have gained popularity as potential biomarkers for sarcopenia. Irisin is a recently identified myokine, but its role in pathological sarcopenia remains unclear. We investigated the validity and accuracy of circulating irisin levels as a potential biomarker for sarcopenia.
  
  
  METHODS
  We evaluated the anthropometrics, body composition, sarcopenia-related parameters and serum irisin levels of 715 community-dwelling Koreans. Sarcopenia was determined on the basis of the clinical diagnostic criteria of muscle atrophy and weakness, which were proposed by the Asian Working Group for Sarcopenia.
  
  
  RESULTS
  Circulating irisin levels were correlated with appendicular lean mass/height2(rmen= 0.275; rwomen= 0.321) and handgrip strength (rmen= 0.219; rwomen= 0.312) in both sexes (all P < 0.01). Furthermore, the mean circulating irisin levels were lower in the sarcopenia group than in the normal group (all P < 0.05). In the logistic regression models, the association between serum irisin concentration and incident sarcopenia persisted even after adjusting for potential confounders, such as sex, age and fat indices (odds ratio 0.20, 95% CI 0.07-0.60; P for trend <0.01). The predictive values of serum irisin for sarcopenia were <1.0 μg/mL in men and <1.16 μg/mL in women, with the area under the receiver operating characteristic curves of 0.87 (95% CI 0.77-0.99) and 0.68 (95% CI 0.55-0.81), respectively (all P < 0.01).
  
  
  CONCLUSIONS
  A low level of circulating irisin is a sensitive marker for muscle weakness and atrophy. Irisin is a potential biomarker for muscle dysfunction that could help predict the onset of sarcopenia and provide new avenues for monitoring age-related muscle changes. Geriatr Gerontol Int 2017; 17: 2266-2273.
authors.affiliation: Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Korea.|Yonsei Institute of Sports Science and Exercise Medicine, Korea.
authors.forename: Jae Seung
authors.initials: JS
authors.lastname: Chang
authors.affiliation: Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Korea.|Yonsei Institute of Sports Science and Exercise Medicine, Korea.
authors.forename: Tae Ho
authors.initials: TH
authors.lastname: Kim
authors.affiliation: Department of Physiology, Tan Tao University College of Medicine, Long An, Vietnam.
authors.forename: Tuyet Thi
authors.initials: TT
authors.lastname: Nguyen
authors.affiliation: Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Korea.
authors.forename: Kyu-Sang
authors.initials: KS
authors.lastname: Park
authors.affiliation: Keimyung University College of Nursing, Daegu, Korea.
authors.forename: Nahyun
authors.initials: N
authors.lastname: Kim
authors.affiliation: Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Korea.|Yonsei Institute of Sports Science and Exercise Medicine, Korea.
authors.forename: In Deok
authors.initials: ID
authors.lastname: Kong
mesh_terms: D015415:Biomarkers / Q000097:blood; D003430:Cross-Sectional Studies; D005260:Female; D005353:Fibronectins / Q000097:blood*; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D055948:Sarcopenia / Q000097:blood / Q000175:diagnosis*
chemical_list: D015415:Biomarkers; C577593:FNDC5 protein, human; D005353:Fibronectins
keywords: biomarker; irisin; muscle weakness; muscular atrophy; sarcopenia