Rheumatoid factor (RF): RF antibodies collect in the synovium, or tissue lining of your

joints. They are present in the blood of many people with RA. Erythrocyte sedimentation

rate (ESR): A high erythrocyte sedimentation rate may indicate inflammation in your joints.A

positive rheumatoid factor test result indicates that a high level of rheumatoid factor was

detected in your blood. A higher level of rheumatoid factor in your blood is closely

associated with autoimmune disease, particularly rheumatoid arthritis.