BackTesting for Rheumatoid Arthritis Understand the lab and imaging tests used to diagnose and monitor disease activity in RA.By Mary Anne Dunkin | June 12, 2022Diagnosing 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....