The normal value of troponin is less than 0.04ng/mL, and the specific reference range may vary slightly from hospital to hospital and from testing center to testing center due to different test kits. Troponin is present in cardiac muscle cells and can be detected in the blood when the myocardium is necrotic, and is specific for the diagnosis of myocardial necrosis. Troponin elevation can be detected in the blood when the myocardial cells are necrotic for about 4 hours. There are the following diseases: 1. Acute myocardial infarction, when severe chest pain occurs and is not relieved by nitroglycerin, if troponin is found to be elevated in the laboratory, the diagnosis of acute myocardial infarction can be confirmed in combination with electrocardiogram. 2. 2. Viral myocarditis can also have elevated troponin, with symptoms of viral infection before onset, such as fever, malaise, nausea, vomiting, chest tightness, shortness of breath, dyspnea, etc. The diagnosis can be confirmed by combining ECG, troponin and other myocardial enzymatic tests, and troponin is of great value in confirming myocardial damage, especially for the diagnosis of myocardial infarction.