DR P MARAZZI / SCIENCE PHOTO LIBRARY Diagnosis of Rheumatoid Arthritis Clinical criteria Serum rheumatoid factor (RF), anticyclic citrullinated peptide (anti-CCP), and erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP) X-rays Rheumatoid arthritis should be suspected in patients with polyarticular, symmetric arthritis, particularly if the wrists and 2nd and 3rd metacarpophalangeal joints are involved.