Creatine Kinase(CK) Determination Reagent is an in vitro diagnostic quantitative test kit. This test is used for diagnosis and monitoring the muscular diseases, muscular injuries and muscular inflammation (myositis). CK is an enzyme that mainly exists in your heart and skeletal muscle, with small amounts in your brain. The cells in your skeletal muscles, heart muscles or brain release creatine kinase into your blood when they’re damaged.