Serum enzymes are substances that play a catalytic function in the body and can be divided into two categories according to their distribution location: plasma-specific enzymes and non-plasma-specific enzymes. 1. plasma-specific enzymes: the concentration in plasma is very high, and most of them are synthesized in the liver, such as thrombin, lipoprotein lipase and so on. The function of thrombin is to participate in the endogenous or exogenous coagulation pathway of the body, so that fibrinogen is converted to fibrin to achieve the purpose of hemostasis. 2. Non-plasma specific enzymes: the content in plasma is low and can be divided into secretory enzymes and intracellular metabolizing enzymes. Secretory enzymes from exocrine glands, such as trypsin, etc., are inactivated in the blood, and the specific content can be indicative of certain diseases; intracellular metabolizing enzymes, such as aminotransferases, are involved in the intracellular metabolism, and enter into the bloodstream when the cells are damaged. Serum enzymes are important catalytic media in the body, and play a very important role in the homeostasis of the organism. Serum enzymes need to be examined under the guidance of a doctor to carry out standardized operations, and should not be judged on their own.