title: Creatine kinase as a marker of obesity in a multi-ethnic population.
abstract: Creatine kinase (CK), the central regulatory enzyme of energy metabolism, is particularly high in type II skeletal muscle fibers, which are associated with insulin resistance and obesity. As resting plasma CK is mainly derived from skeletal muscle, we assessed whether plasma CK is associated with markers of obesity.
  
  
  
  In this cross-sectional study, we analyzed a random sample of the multi-ethnic population of Amsterdam, the Netherlands, consisting of 1444 subjects aged 34-60 years. The primary outcome was the independent association between plasma CK after rest and waist circumference. Other outcomes included waist-to-hip ratio and body mass index.
  
  
  
  Mean waist circumference increased from the first through the third CK tertile, respectively 90.3 (SD 13.4), 93.2 (SD 14.3), and 94.4 (SD 13.3) cm (p < 0.001 for differences between tertiles). The increase in waist circumference was 8.91 (95% CI 5.35 to 12.47) cm per log CK increase after adjustment for age, sex, African ethnicity, educational level, physical activity and plasma creatinine. Similarly, CK was independently associated with waist-to-hip ratio and body mass index, with an increase of respectively 0.05 (95% CI 0.03 to 0.07) and 3.6 (95% CI 2.3 to 5.0) kg/m2per log CK increase.
  
  
  
  Plasma CK is independently associated with measures of obesity in a multi-ethnic population. This is in line with the central role of type II skeletal muscle fibers in energy metabolism and obesity. Prospective studies should assess whether resting plasma CK could be an easy accessible marker of CK rich type II fiber predominance that helps identify individuals at risk for obesity.
authors.affiliation: Department of Vascular Medicine, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands. Electronic address: mail@lizzybrewster.net.
authors.forename: Yentl C
authors.initials: YC
authors.lastname: Haan
authors.affiliation: Department of Vascular Medicine, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
authors.forename: Inge
authors.initials: I
authors.lastname: Oudman
authors.affiliation: Department of Vascular Medicine, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands; Department of Cardiology, Academic Hospital Paramaribo, Flustraat 1, Paramaribo, Suriname.
authors.forename: Frederieke S
authors.initials: FS
authors.lastname: Diemer
authors.affiliation: Department of Vascular Medicine, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
authors.forename: Fares A
authors.initials: FA
authors.lastname: Karamat
authors.affiliation: Department of Social Medicine, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
authors.forename: Irene G
authors.initials: IG
authors.lastname: van Valkengoed
authors.affiliation: Department of Vascular Medicine, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands; Department of Internal Medicine, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
authors.forename: Gert A
authors.initials: GA
authors.lastname: van Montfrans
authors.affiliation: Department of Vascular Medicine, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands; Department of Social Medicine, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands; Department of Internal Medicine, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands; Department of Public Health, Anton de Kom University of Suriname, Paramaribo, Suriname.
authors.forename: Lizzy M
authors.initials: LM
authors.lastname: Brewster
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood*; D015992:Body Mass Index; D003402:Creatine Kinase / Q000097:blood*; D003430:Cross-Sectional Studies; D004734:Energy Metabolism / Q000502:physiology; D005006:Ethnicity; D015444:Exercise / Q000502:physiology; D005260:Female; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood*; D012307:Risk Factors; D055105:Waist Circumference / Q000502:physiology; D049629:Waist-Hip Ratio / Q000379:methods
chemical_list: D015415:Biomarkers; D003402:Creatine Kinase
keywords: Creatine kinase; Energy metabolism; Glucose tolerance; Obesity; Skeletal muscle fiber type