Creatine kinase (CK) enzyme is found in heart and skeletal muscle and to a lesser extent brain. When damage is done to these types of tissue CK is released into the blood. There are three isoenzymes, and depending on which one is elevated this lab value can help determine timing, location, extent of damage. The three isoenzymes are CK-MB (cardiac), CK-MM (skeletal), and CK-BB (brain).