Getting a diagnosis of RA can be a difficult process and may take some time to accomplish. In its early stages, RA may resemble other forms of arthritis. No single test can confirm RA, and making a firm diagnosis may take time. Your doctor will check your medical history, keep a close watch on your symptoms and conduct certain tests to help determine RA.
• Medical history. Your doctor will ask about your joint symptoms (pain, tenderness, stiffness, difficulty moving) – how and when they started, if they come and go, how severe they are and if anything makes them better or worse. The number and location of joints involved can also indicate RA; the disease tends to affect the same joint on both sides of the body. However, it is possible for the disease to develop in a single joint.
• Physical exam. Your doctor should examine each joint, looking for tenderness, swelling, warmth and painful or limited movement. An overall physical exam may reveal other signs, such as rheumatoid nodules or a low-grade fever.
• Blood tests. Two types of blood tests are used. One measures inflammation levels. The other type looks for biomarkers such as antibodies (blood proteins) linked with RA.
• Erythrocyte sedimentation rate (ESR, or “sed rate”) and C-reactive protein (CRP) level are markers for inflammation. A high ESR or CRP combined with other clues to RA helps make the diagnosis.
• Rheumatoid factor (RF) is an antibody found in about 80 percent of people with RA over time. Antibodies to cyclic citrullinated peptide (CCP) are found in 60 to 70 percent of people with RA and can exist even before symptoms start. They are, however also found in people without RA.
• Imaging tests. RA can cause erosions – when the ends of the bones within a joint break down. An X-ray, ultrasound, or MRI (magnetic resonance imaging) scan may be done to look for erosions. Their absence doesn’t rule out RA, however. It may mean that RA is in an early stage and hasn’t yet damaged bone. Early imaging results can also help monitor how well treatment is working.