Clinical Information

Non-rheumatoid and rheumatoid arthritis (RA) populations are not clearly separate with regard to the presence of rheumatoid factor (RF). Patients with various non-rheumatoid diseases characterized by chronic inflammation may test positive for RF. These diseases include systemic lupus erythematosus, polymyositis, tuberculosis, syphilis, viral hepatitis, infectious mononucleosis, and influenza. RF factor antibodies have been observed in non-affected individuals, particularly in patients 60 years of age or older.