The novel myokine irisin: clinical implications and potential role as a biomarker for sarcopenia in postmenopausal women

Purpose: To clarify the association of circulating irisin with muscle, liver and bone, and to evaluate irisin as a biomarker for sarcopenia in postmenopausal women. Methods: Quadriceps cross-sectional area (QcCSA), bone mineral density (BMD), liver attenuation (measured in Hounsfield units (HU)) were assessed using quantitative computed tomography in 153 postmenopausal women, mean age of 72.20 ± 5.96 years. Muscle strength and physical performance were evaluated by handgrip test and short physical performance battery, respectively. Serum irisin was measured by an enzyme-linked immunosorbent assay kit. In addition, 147 young women were recruited as a reference group to define cut-off values for sarcopenia. Results: Circulating irisin was positively correlated with QcCSA/body weight (BW) and liver HU even after adjusting for multiple covariates, and the serum level was significantly lower in the sarcopenia group (QcCSA/BW<-2SD of the mean values for young women) than in the presarcopenia (-2SD≤QcCSA/BW<-1SD) or control groups (1SD≤QcCSA/BW<2SD). Logistic regression models showed that the relationship between circulating irisin and prevalence of sarcopenia remained significant after adjusting for confounding factors (per 1.0 ng/mL decrease of irisin, odds-ratio = 1.95, 95% confidence interval 1.33-2.87, p-value = 0.001). Conclusions: In postmenopausal women, serum irisin may be used as a biomarker for sarcopenia, and we showed the potential for the development of irisin-based early screening and staging tool for sarcopenia. ; restriction