The cardiac enzyme profile contains many kinds of enzymes, mainly consisting of lactate dehydrogenase (LDH), glutamate transferase (ALT), glutamic aminotransferase (AST), creatine kinase (CK) and its isoenzymes (CK-MB), and alpha-hydroxybutyrate dehydrogenase (alpha-HBDH). Under normal circumstances they maintain a certain range of concentration in the human body, and when inflammation or trauma caused by various reasons, the concentration in the body increases, and usually the test can guide the disease treatment and determine the prognosis. I. Lactate dehydrogenase (LDH) Lactate dehydrogenase is widely present in various tissues of the body, with the most abundant in cardiac muscle, skeletal muscle and kidney, followed by liver, spleen, pancreas, lung and tumor tissue, etc. Therefore, LDH has a high sensitivity for diagnosis, but poor specificity. Second, glutathione transferase (ALT) and glutathione aminotransferase (AST) ALT is mainly distributed in the liver, followed by skeletal muscle, kidney and cardiac muscle. AST is mainly distributed in the cardiac muscle, followed by liver, skeletal muscle and kidney tissues. In hepatocytes, ALT is mainly found in non-mitochondria, while about 80% of AST is found in mitochondria. Creatine kinase (CK) is mainly found in skeletal muscle, cardiac muscle, brain, thyroid, lung tissue, and gastrointestinal smooth muscle, with the highest content in skeletal muscle, followed by cardiac muscle, then followed by brain and gastrointestinal smooth muscle. IV. Creatine kinase isoenzyme (CK-MB) Creatine kinase (CK) is a dimer composed of 2 subunits, forming 3 different isoforms: ①CK-MM (CK3), mainly present in skeletal muscle and cardiac muscle, CK-MM can be divided into MM1, MM2 and MM3 isoforms. MM3 is the main form of CK-MM present in myocytes. ②CK-MB (CK2), mainly exists in cardiac muscle. ③CK-BB (CK1), mainly present in brain, prostate, lung, intestine and other tissues. CK-MM is predominant in the blood of normal people, and the amount of CK-BB is extremely small. The detection of different isoforms of CK is of great value in identifying the causes of CK elevation. V. α-Hydroxybutyrate dehydrogenase (α-HBDH) α-HBDH is mainly distributed in cardiac muscle, kidney, red blood cells, etc. It should be noted that the above-mentioned enzymes lack specificity (that is, they are not produced by one organ or tissue alone), so when there is an elevation, it needs to be analyzed in conjunction with gender, age, race, physiological status, presence of sports trauma, infection, etc. to make a comprehensive judgment. We should not jump to conclusions at the first sign of elevation.