Rheumatoid factor (RA factor) Blood Negative To diagnose and prognose the Rheumatoid Arthritis Rheumatoid Arthritis Sjögren's Syndrome Systemic Lupus erythematosus Dermatomyositis Scleroderma Polymyositis Waldenstrom's Disease Sarcoidosis Infectious Mononucleosis Subacute bacterial endocarditis Tuberculosis Chronic lung disease Chronic liver disease Severe lipemia Circulating immune complex