title: Serum levels of the myokine irisin in relation to metabolic and renal function.
abstract: OBJECTIVE
  Irisin has recently been introduced as a novel myokine which reverses visceral obesity and improves glucose metabolism in mice. However, regulation of irisin in humans in relation to renal and metabolic disease has not been comprehensively studied.
  
  
  METHODS
  Serum irisin levels were quantified by ELISA and correlated with anthropometric and biochemical parameters of renal function, glucose and lipid metabolism, as well as inflammation, in 532 patients with stages 1-5 of chronic kidney disease (CKD).
  
  
  RESULTS
  Median serum irisin levels adjusted for age, gender, and BMI significantly decreased with increasing CKD stage and lowest concentrations were seen in patients with CKD stage 5. Furthermore, irisin concentrations were associated with facets of the metabolic syndrome including diastolic blood pressure, markers of impaired glucose tolerance, and dyslipidemia in univariate analysis. Moreover, markers of renal function, e.g. glomerular filtration rate, and insulin resistance, e.g. homeostasis model assessment of insulin resistance, remained independently associated with circulating irisin levels in robust multivariate analysis.
  
  
  CONCLUSIONS
  We show that irisin serum concentrations decrease with increasing CKD stage and are independently and positively predicted by renal function and insulin resistance. The physiological relevance of our findings, as well as the factors contributing to irisin regulation in humans, needs to be further defined in future experiments.
authors.affiliation: Department of Endocrinology and Nephrology, University of Leipzig, Liebigstraße 20, 04103 Leipzig, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Ebert
authors.forename: Denise
authors.initials: D
authors.lastname: Focke
authors.forename: David
authors.initials: D
authors.lastname: Petroff
authors.forename: Ulrike
authors.initials: U
authors.lastname: Wurst
authors.forename: Judit
authors.initials: J
authors.lastname: Richter
authors.forename: Anette
authors.initials: A
authors.lastname: Bachmann
authors.forename: Ulrike
authors.initials: U
authors.lastname: Lössner
authors.forename: Susan
authors.initials: S
authors.lastname: Kralisch
authors.forename: Jürgen
authors.initials: J
authors.lastname: Kratzsch
authors.forename: Joachim
authors.initials: J
authors.lastname: Beige
authors.forename: Ingolf
authors.initials: I
authors.lastname: Bast
authors.forename: Matthias
authors.initials: M
authors.lastname: Anders
authors.forename: Matthias
authors.initials: M
authors.lastname: Blüher
authors.forename: Michael
authors.initials: M
authors.lastname: Stumvoll
authors.forename: Mathias
authors.initials: M
authors.lastname: Fasshauer
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D003971:Diastole; D050171:Dyslipidemias / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005353:Fibronectins / Q000097:blood*; D005919:Glomerular Filtration Rate; D018149:Glucose Intolerance / Q000097:blood*; D006801:Humans; D006973:Hypertension / Q000097:blood*; D007249:Inflammation / Q000097:blood; D007333:Insulin Resistance; D007676:Kidney Failure, Chronic / Q000097:blood; D008297:Male; D024821:Metabolic Syndrome / Q000097:blood*; D008875:Middle Aged; D015999:Multivariate Analysis; D051436:Renal Insufficiency, Chronic / Q000097:blood*; D012720:Severity of Illness Index
chemical_list: C577593:FNDC5 protein, human; D005353:Fibronectins