Background Creatine kinase (CK) elevation is occasionally encountered in gout subjects without any clinical manifestation of a neuromuscular disorder. To our knowledge no data have been published to systematically describe the extent of this association.

Objectives The objective of this work is to report on the frequency of isolated CK elevation in a gout population, to compare it with a reference population, namely non gouty subjects with type-2 diabetes mellitus, and to formulate recommendations for clinical practice and subjects' monitoring during clinical studies.

Methods CK values from subjects screened in four gout clinical studies and two type-2 diabetes studies were collected. Descriptive statistics mean, median, and dispersion were reported. The frequency and level of abnormal values (based on central laboratory determination) were further described and compared between groups. For abnormal values clinical correlation were sought.

Results CK values were available for 1,059 gout subjects and 1,963 diabetes subjects. Means, including comparison between gout and diabetes, standard deviations, medians and ranges are provided in the following table.

Using normal laboratory values of 24-195 UI/L, 276/1,059 (26%) subjects with suspected gout and 207/1,963 (10.5%) subject with diabetes had abnormally elevated CK values. The frequency of subject with >3 times the upper limit of normal was 28/1059 (2.6%) in gout subjects and 13/1963 (0.7%) in diabetes subjects.

Conclusions Overall, CK are significantly higher in a gout population when compared to a diabetic population. A clinically significant proportion of gout patients have abnormally elevated CK when screened for participating in a clinical study. Abnormally elevated CK in a gout subject could be due to concomitant medications frequently prescribed in this group (such as colchicine or statins) or recreational (exercise-induced). The possibility that CK elevation could be due to tendinous/muscular deposition of uric acid, while suggested by some case-reports in the literature, remains a hypothesis that need to be further tested.

Disclosure of Interest Y.-J. Choi Shareholder of: cymabay therapeutics, Employee of: cymabay therapeutics, A. Steinberg Shareholder of: cymabay therapeutics, Employee of: cymabay therapeutics, P. Boudes Shareholder of: cymabay therapeutics, Employee of: cymabay therapeutics