Testing for Rheumatoid Arthritis

By Mary Anne Dunkin | June 12, 2022 Diagnosing rheumatoid arthritis (RA) can take time. Like other forms of arthritis, a diagnosis is based largely on the findings from a medical exam and your symptoms. These may include joint pain, tenderness and swelling that affects the same joint or joints on both sides of your body (like both wrists or both knees); fatigue and fever. Lab tests and imaging tests can help your doctor make the diagnosis.

Diagnostic Lab Tests

Evidence of RA may be seen in the blood, so blood tests play an important role in making a diagnosis. Following are some of the tests your doctor may order.

• Erythrocyte sedimentation rate (ESR or sed rate). The ESR can gauge how much inflammation is in your body by measuring how quickly red blood cells (erythrocytes) separate from other cells in the blood and collect as sediment in the bottom of a test tube. Because inflammation can be caused by conditions other than RA, the results must be considered along with those of other tests when making an RA diagnosis.
• C-Reactive Protein (CRP). This measures levels of CRP, a protein produced by the liver that signals inflammation. High CRP levels are common in RA and other inflammatory forms of arthritis. Because a high CRP may be present with many diseases and conditions, a high CRP in itself does not mean you have arthritis or identify which form you may have. The results must be interpreted in the context of your symptoms as well as the results of other tests.
• Rheumatoid factor (RF). Rheumatoid factor is a protein made by the immune system which may attack healthy tissues. High levels of rheumatoid factor could help your doctor make a diagnosis of RA. However, RF levels may also be high in other autoimmune diseases, so an RF test alone cannot be used to diagnose RA.
• Anti-CCP antibody test ( ACCP or CCP ). This test is for a type of autoantibody called cyclic citrullinated peptide (CCP) antibodies, which can be found in the blood of 60% to 80% of people with rheumatoid arthritis. The test is often conducted along with an RF test.
• Antinuclear antibody test (ANA). Antinuclear antibodies (ANA) are a type of autoantibody, a protein that attacks your body’s own tissues. The presence of ANAs can indicate an autoimmune condition, including RA.

Diagnostic Imaging Tests

Imaging tests, along with the physical exam and laboratory tests, can help identify RA. These imaging tests may be used to diagnose RA.

• X-ray. X-rays can show bone damage, characteristic of RA, where they meet at joints. They are a common tool in diagnosis; however, because it damage from inflammation develops over time and may not be visible via X-ray early on, it may not be useful for diagnosing early RA.
• Magnetic resonance imaging (MRI). MRI is procedure in which radio waves and a powerful magnet linked to a computer are used to create 3D images of structures inside the body. MRI can show changes in cartilage and bone that are indicative of RA.
• Ultrasound. Ultrasound, or sonography, uses sound waves to create pictures of structures inside the body. THis may be used to view changes in bones and cartilage suggestive of RA before any changes show up on X-ray. Other benefits of ultrasound include its relatively low cost and the fact it doesn’t expose the body to radiation, like X-ray.
• Computed tomagraphy (CT) scan. A CT scan is an imaging procedure that combines a series of X-ray images to create cross-sectional images of parts of the body. Studies show CT scans may be effective for viewing early bone erosions that occur with RA.