Serum proteins are, as the name suggests, the proteins in the blood serum, with two other components, one is albumin and the other is globulin. Albumin is produced in the liver and has a very small molecular weight but high density. It plays an important role in maintaining the body’s nutrition and colloid osmotic pressure. Clinically, if the body’s serum protein concentration falls below 25 g/L, the body’s colloid osmotic pressure will drop, and the water inside the blood vessels will seep outside the vessels, leading to tissue edema. In addition, globulin is an antibody secreted by B lymphocytes. The molecular weight of globulin is very large and it has an important role mainly in humoral immunity.