CK-MB refers to creatine kinase isoenzyme. It is relatively specific for the diagnosis of myocarditis and acute myocardial infarction, and is more specific than other cardiac enzymes, but not as specific as troponin, but it is not only elevated in myocarditis and myocardial infarction, but also in conditions such as hypothyroidism, myolysis, autoimmune diseases, and heart failure. There are also creatine kinase isoenzymes that are abnormal while creatine kinase is normal. This can occur in patients with tumors or laboratory errors, or it can be caused by the presence of giant cells. In patients with elevated creatine kinase isoenzyme, troponin needs to be checked further.