CK is an abbreviation for creatine kinase, which is a type of cardiac enzyme that requires a blood test. In clinical practice, this indicator is mainly used to determine whether the patient has myocarditis or acute myocardial infarction, but its specificity for diagnosing this type of disease is not very high, and it is only a relatively common preliminary blood test. The creatine kinase test should be combined with the creatine kinase isoenzyme test and troponin test, and the specificity of the latter two is higher for the diagnosis of myocarditis or myocardial infarction. In addition to the above diseases, hypothyroidism, muscle injury, rhabdomyolysis, fractures, tumors, and severe infections may also cause elevated creatine kinase.