1874-2416/09 2009 Bentham Open Open Access Pairs of Creatine Kinase Serum Activity

versity Hospital of Tübingen Abstract: Background: For patients with an increased risk of developing myopathy with statin treatment, guidelines rec-ommend to measure CK before and 6-12 weeks after initiating statin treatment. Further, in clinical trials of statins, the number of patients experiencing elevated creatine kinase (CK) serum activity is commonly reported as a safety parameter. Usually exceeding the upper limit of normal (ULN) is used as the basis of description to characterize muscular damage potentially caused by statins. Therefore, basic data on both, proportions of patients with specific CK increases, and abso-lute and relative CK increases, would be helpful to assess potential CK chances in patients. However, no such data are available so far. Methods: CK activity was measured in a group of blood donors (n=40) at two occasions 10 weeks apart. The 95 th percen-tile of absolute and relative CK increases was selected to separate true from irrelevant changes. A CK difference was de-fined to be true if a random measurement error of 10 % was exceeded. The numbers of subjects with true CK differences were characterised by both measurements being under, crossing, or being above ULN, and twice ULN, respectively. Results: Five percent of subjects (9