Common causes of rheumatoid factor IgG109g/L include autoimmune and infectious diseases such as rheumatoid arthritis. Treatment should be based on different causes. Rheumatoid arthritis: Rheumatoid factor IgG109g/L suggests that the high titer of rheumatoid factor is positive, the first consideration is rheumatoid arthritis, usually accompanied by joint swelling and pain, and can be given under the guidance of the doctor, celecoxib, methotrexate and other drugs to fight rheumatism. Other autoimmune diseases: other autoimmune diseases such as vasculitis can also cause elevated rheumatoid factor, need to be clearly diagnosed and follow the doctor’s instructions to use thalidomide, cyclophosphamide, dexamethasone and other treatments. Infectious diseases: Infectious diseases such as infectious mononucleosis can also cause rheumatoid factor IgG elevation, usually accompanied by fever and other symptoms of infection, need to carry out anti-infection treatment. Rheumatoid factor IgG109g/L may also have other causes, we suggest that patients go to the rheumatology and immunology department of regular hospitals to have a detailed consultation and follow the prescribed treatment.