A higher than normal rheumatoid factor is not unique to rheumatoid arthritis, but can be found in many acute and chronic inflammatory conditions, and even in a small percentage of healthy individuals. Therefore, rheumatoid arthritis should not be diagnosed clinically on the basis of a positive rheumatoid factor alone. Early diagnosis of rheumatoid immune diseases is sometimes difficult and requires close attention to clinical manifestations and regular review of relevant indicators. Rheumatic diseases 1. rheumatoid arthritis, lupus erythematosus, scleroderma, mixed connective tissue disease, dry syndrome; 2. acute viral infections; 3. infectious mononucleosis, hepatitis, influenza. Parasitic infections 1, trypanosomiasis, filariasis, schistosomiasis, black fever, malaria; 2, chronic inflammatory diseases; 3, tuberculosis, leprosy, yellow fever, syphilis, brucellosis, subacute endocarditis, salmonellosis. Oncology 1, after radiotherapy or chemotherapy; 2, other hyperglobulinemic states; 3, hypergammaglobulinemic purpura, cold globulinemia, chronic liver disease, nodular disease, other chronic lung diseases (e.g., idiopathic interstitial pulmonary fibrosis).