Immunoglobulins are a group of proteins with antibody activity, present in gammaglobulin and immunoglobulin G, immunoglobulin A, immunoglobulin M, immunoglobulin D and immunoglobulin E. The first three are mainly measured clinically. Under normal conditions, antibodies do not act on human tissues. Only in pathological conditions, when the normal human tissues are altered and antigenicity is formed, the body produces the corresponding antibodies to bind to them. Changes in the level of immunoglobulins often occur in many diseases, especially immunological diseases, such as immunodeficiency diseases, which are seen in reduced levels in the serum. Immunoglobulins are elevated in autoimmune diseases such as lupus erythematosus and rheumatoid arthritis. In some infectious diseases, increased levels of immunoglobulins can also be seen. Therefore, immunoglobulin measurement is a non-specific test that can only indicate how well the body is functioning immunologically, but not what the disease is. Immunoglobulin G is the antibody with the highest content in human serum, accounting for 70%-80% of serum immunoglobulins, and is the most important antibody in the body, which has strong resistance to various bacteria and viruses. Generally the anti-nuclear antibodies in lupus erythematosus are in immunoglobulin G. Therefore, the patient’s immunoglobulin G level can be increased, while other immunoglobulins can also have changes.