Rheumatoid Arthritis Diagnosis
There is no single lab test can definitively diagnose rheumatoid arthritis. However, there are several blood tests that may be ordered to detect changes in the body that are indicative of rheumatoid arthritis.
Commonly used blood tests measure the presence of rheumatoid factor (RF), anti-cyclic citrullinated peptide (called ACPA or anti-CCP), and inflammatory markers such as erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). These tests are also used to help diagnose other inflammatory conditions—for example, CRP may be used to diagnose heart disease.
A doctor may order imaging if the patient’s clinical evaluation and lab tests did not provide enough information to diagnose or rule out rheumatoid arthritis. Imaging allows the doctor to see if there is evidence of joint damage.
Ultrasound. This imaging technology is used to detect inflammation of the delicate synovial tissue that encapsulates some joints and tendons. This inflammation, called synovitis, is the hallmark symptom of rheumatoid arthritis. Ultrasound can also detect tenosynovitis in the finger, which some researchers believe to be an early sign of RA.
Ultrasound is performed using either traditional “b-mode” (gray scale) or power Doppler. While less common and more expensive, power Doppler can detect the flow of blood, allowing a physician to see if the synovial inflammation is active.