Serum globulin is a serum protein that exists in the human body. It is also known as immunoglobulin because it has an immune effect. A low serum globulin may indicate a certain disease, and the common causes are: 1) low immune function; 2) immunosuppressive drugs; 3) lower globulin due to certain liver diseases, such as severe hepatitis, cirrhosis, liver cancer, etc. Therefore, if low globulin is found in the blood test, further tests should be completed to clarify the specific cause.