This is because of the complexity of blood composition. Some physiological indexes can be obtained only by testing serum, but some diseases and pathological phenomena are complicated and need to be tested with whole blood. Only the types of tests are different (such as blood routine, liver and kidney function, blood sugar, diabetes, blood lipid, hepatitis B, syphilis, hepatitis C, etc. ). Simply put, in order to facilitate the detection and save the detection time, at the same time, taking several tubes of blood and testing parameters can greatly shorten the detection time and provide support for the subsequent treatment of related diseases.