What is the difference between high creatine kinase isoenzyme and low creatine kinase isoenzyme?

Creatine kinase isoenzyme exists in skeletal muscle, myocardium and brain tissue. Elevated creatine kinase isoenzyme in blood is found in muscle injury, which may also be caused by myocardial ischemia, viral myocarditis, polymyositis, epilepsy, etc. Staying up late and strenuous exercise can also lead to elevated values of this examination.