Rheumatoid Arthritis Diagnosis
A primary care physician may suspect RA based in part on a person's signs and symptoms. If so, the patient will be referred to a rheumatologist – a specialist with specific training and skills to diagnose and treat RA. In its early stages, RA may resemble other forms of inflammatory arthritis. No single test can confirm RA. To make a proper diagnosis, the rheumatologist will ask questions about the personal and family medical history, perform a physical exam and order diagnostic tests.
The doctor will ask about personal and family medical history as well as recent and current symptoms (pain, tenderness, stiffness, difficulty moving).
Thedoctor will examine each joint, looking for tenderness, swelling, warmth and painful or limited movement. The number and pattern of joints affected can also indicate RA. For example, RA tends to affect joints on both sides of the body. The physical exam may reveal other signs, such as rheumatoid nodules or a low-grade fever.
The blood tests will measure inflammation levels and look 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 of inflammation. A high ESR or CRP is not specific to RA, but when combined with other clues, such as antibodies, helps make the RA diagnosis.
Rheumatoid factor (RF) is an antibody found in about 80 percent of people with RA during the course of their disease. Because RF can occur in other inflammatory diseases, it’s not a sure sign of having RA. But a different antibody – anti-cyclic citrullinated peptide (anti-CCP) – occurs primarily in patients with RA. That makes a positive anti-CCP test a stronger clue to RA. But anti-CCP antibodies are found in only 60 to 70 percent of people with RA and can exist even before symptoms start.
An X-ray, ultrasound or magnetic resonance imaging scan may be done to look for joint damage, such as erosions, a loss of bone within the joint and narrowing of joint space. But if the imaging tests don’t show joint damage that doesn’t rule out RA. It may mean that the disease is in an early stage and hasn’t yet damaged the joints.