High immunoglobulin G is usually caused by inflammatory stimuli or diseases, such as immunoproliferative and autoimmune diseases, as well as some allergic diseases. 1. Immunoproliferative diseases: If the patient has only monoclonal high immunoglobulin G, immunoproliferative diseases, such as IgG-type secretory multiple myeloma, it is recommended to go to the hospital for a detailed examination such as bone marrow aspiration. 2. Autoimmune diseases: patients with rheumatoid arthritis, dry syndrome and systemic lupus erythematosus may have high immunoglobulin G due to immune dysfunction. 3. Allergic diseases: Some allergic diseases, such as allergic rhinitis, atopic dermatitis, urticaria, will also find high immunoglobulin G during the examination, which is a manifestation of the body’s autoimmune system to fight against the disease. High immunoglobulin G may also have other causes, it is recommended to go to the hospital in time, complete the examination to clarify the cause of the disease, and then give targeted treatment or therapy.