Rheumatoid arthritis (RA) is a disease characterized by chronic progressive and symmetrical arthritis, which can be accompanied by extra-articular systemic damage. It is one of the common rheumatic diseases, mostly seen in women aged 30 to 50 years. The prevalence in our population is 0.32% to 0.38%, which is lower than the 1% to 2% of whites in Europe and America. The early pathological changes are mainly synovial inflammation of the joints, with clinical manifestations of joint swelling, pain, numbness, morning stiffness, and unfavorable activities; later inflammation continues to leach, and when cartilage and bone are involved, it can lead to destruction of joint structure, deformity and dysfunction, resulting in different degrees of disability. The cause of this disease is not yet clear, its pathogenesis is related to autoimmune abnormalities, so far there is no curative drug, but early diagnosis, early treatment, early patients can mostly obtain good control, so as to avoid deformation and disability; intermediate and late patients can also be actively treated to stop the progress of the disease, to protect the workforce, improve the quality of life, and maintain health status. I. What is rheumatoid factor? What is its clinical significance? Rheumatoid factor (RF) is an autoantibody used to detect certain antigens in the patient’s serum, which is divided into IgA-RF, IgM-RF, IgE-RF, IgG-RF and so on according to its type. -RF, both usually referred to as RF. patients with high clinical suspicion of rheumatoid arthritis, most of the RF test is positive, but some patients are negative, that is, the different types listed above, can be detected by other special methods. Rheumatoid factor (RF) has a positive rate of about 50% to 70% in rheumatoid arthritis and is one of the important serological criteria for the diagnosis of rheumatoid arthritis. Persistent high titers of RF often indicate active rheumatoid arthritis, a high incidence of bone erosion, and a poor prognosis. High titers of RF can also be seen in other rheumatic diseases, such as: (1) autoimmune diseases systemic lupus erythematosus, dry syndrome, mixed connective tissue disease, systemic sclerosis, polymyositis/dermatomyositis, IgA nephropathy, etc. (2) Infectious diseases hepatitis, tuberculosis, bacterial endocarditis, schistosomiasis. (3) Non-infectious diseases diffuse interstitial lung fibrosis, nodular disease, macroglobulinemia, etc. Clinically, arthritis is classified into two categories based on RF characterization: RF-positive and RF-negative. A positive RF alone cannot diagnose rheumatoid arthritis, and a negative RF cannot exclude the diagnosis of rheumatoid arthritis. In addition, 5% of the normal population, especially the elderly, will also detect a positive RF. Second, the onset of rheumatoid arthritis and what factors are related? The cause of rheumatoid arthritis is not fully understood, but it is believed that its onset is related to a variety of factors. (1) genetic factors rheumatoid arthritis has a family tendency to develop, rheumatoid arthritis patients have a significantly higher rate of specific gene positivity than normal people. (2) Infectious factors rheumatoid arthritis patients serum anti-EB virus antibodies and anti-Chlamydia antibodies are significantly higher, suggesting that the disease is related to infectious factors. In addition, mycobacteria, cytomegalovirus and retrovirus may be related to rheumatoid arthritis. (3) Endocrine factors are low in women who take birth control pills and pregnancy, and rheumatoid arthritis occurs significantly more after delivery. Men with rheumatoid arthritis have decreased testosterone levels. (4) Other factors such as cold, wet and cold, fatigue, trauma, smoking and mental stimulation.