How Do I Know If I Have Arthritis?
In addition to symptoms and a doctor's exam, blood tests and X-rays are commonly used to confirm rheumatoid arthritis. The majority of people with rheumatoid arthritis have an antibody called rheumatoid factor (RF) in their blood, although RF may also be present in other disorders. A newer test for rheumatoid arthritis that measures levels of antibodies in the blood (called the anti-CCP test) is more specific and tends to be only elevated in patients with rheumatoid arthritis or in patients about to develop rheumatoid arthritis. The presence of anti-CCP antibodies can also be used to predict which patients will get more severe rheumatoid arthritis.
X-rays are used to diagnose osteoarthritis, typically revealing an uneven loss of cartilage and spurring of the underlying bone. Sometimes blood tests and joint aspiration (using a needle to draw a small sample of fluid from the joint for testing) are used to rule out other types of arthritis. If your doctor suspects infectious arthritis, testing a sample of fluid from the affected joint will usually confirm the diagnosis and guide treatment.