What are the diseases that can cause high rheumatoid factor? Rheumatoid factor is an autoantibody. It is mainly found in patients with rheumatoid arthritis, but it is not a specific antibody unique to rheumatoid arthritis (that is, a high rheumatoid factor does not necessarily mean that you have rheumatoid arthritis, and rheumatoid factor is not necessarily high in patients with rheumatoid arthritis!) Rheumatoid factor is positive in about 50% of patients with systemic lupus erythematosus; in other connective tissue diseases, such as systemic sclerosis, dry syndrome, dermatomyositis, etc.; in patients with tuberculosis and chronic active viral hepatitis; and in 10% of normal elderly people.