Race-gender differences in serum creatine kinase activity: a study among South Africans.

Higher levels of total serum creatine kinase activity have been reported in black compared with white North Americans of the same sex. In a study among South Africans, we found such an interracial difference was notable only for males. The difference was heightened by physical activity. This study affirms the importance of sampling the indigenous population when developing a reference range for total creatine kinase activity.