Creatine kinase as a marker of obesity in a multi-ethnic population.

Abstract Objective 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. Methods 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. Results 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 2 per log CK increase. Conclusions 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.