How Rheumatoid Arthritis Is Diagnosed
Unlike diabetes or kidney disease, rheumatoid arthritis (RA) cannot be diagnosed with a simple blood test. Instead, the diagnosis often takes time and is based largely on what the doctor hears from you (the medical history) and observes in you (the physical exam).
During the medical history, your doctor will ask questions about specific joints as well as how you feel in general. Because findings from the medical history play a major role in the diagnosis, it’s important to give your doctor clear and accurate answers to questions, such as the following:
• Do you have pain in many joints? People with rheumatoid arthritis often have pain in several joints at once as opposed to just one.
• Do the same joints on both side of your body hurt at the same time? Symmetric pain is often as sign of rheumatoid arthritis. For example, if one wrist or knee is inflamed or painful, the other wrist or knee will likely be as well.
• When is the pain most severe? People with rheumatoid arthritis often feel worst when they first wake up, and then later in the day when fatigue sets in.
• Have you had periods of feeling weak and uncomfortable all over? Many people with rheumatoid arthritis notice generalized problems, such as muscle aches, fatigue, stiffness, weight loss and flu-like symptoms.
Along with the medical history, a thorough physical exam will supply most of the information needed to make the diagnosis. Rheumatoid arthritis symptoms your doctor will look for in the exam include:
• Joint swelling, warmth and redness
• Joint tenderness
• Loss of motion in your joints
• Joints that are out of alignment
• Signs of rheumatoid arthritis in other organs, such as the heart, lungs or kidneys
After the medical history and physical examination, your doctor may order lab tests and imaging procedures to help confirm your diagnosis. These tests include:
• Erythrocyte sedimentation rate (sed rate), a blood test that measures the rate at which red blood cells sink and form sediment in the bottom of a test tube. An elevated rate indicates inflammation.
• C-reactive protein, a measure of inflammation that indicates disease activity
• Rheumatoid factor, an antibody found in the blood of about 70 percent to 80 percent of people with rheumatoid arthritis
• Antinuclear antibodies (ANA), antibodies that combine with the nuclei of cells and appear in about 30 percent to 40 percent of people with rheumatoid arthritis
• Anti-CCP antibody, an antibody that binds to the amino acid citrulline, which is present in most people with rheumatoid arthritis. There is a 90 percent or greater likelihood that a person has rheumatoid arthritis when this antibody is found in the blood. A positive anti-CCP may indicate a person’s rheumatoid arthritis is more likely to progress quickly and be severe.
• X-rays, which can show swelling of soft tissues and loss of bone density around affected joints
• Bone scans to detect inflammation in joints
• Magnetic resonance imaging (MRI), which can show synovitis, inflammation of the joint lining characteristic of rheumatoid arthritis, before damage shows up on X-ray, as well as inflammation in other organs
