Creatine kinase is an enzyme found in the heart, brain, skeletal muscle, and other tissues.[2] Creatine kinase levels in our blood comes mainly from our muscles.[2] Blood levels of creatine kinase rise when muscle or heart cells are damaged.[2] People with glycogen storage disease type 5 do tend to have a higher resting blood CPK concentration.[3] Normal creatine kinase levels tends to be consid