How Rheumatoid Arthritis Is Diagnosed
A diagnosis of rheumatoid arthritis is based on a combination of:
- Symptoms
- Medical history
- Physical examination
- Blood tests
- Imaging (x-ray, MRI, CT scan, or ultrasound)
In the U.S., a definitive diagnosis is usually based on blood tests and 6 weeks of symptoms, but there has recently been some discussion of changing this to 3 weeks of symptoms in order to get people into treatment earlier.
Your Symptoms and Medical History
Your doctor is likely to begin the appointment by asking about your symptoms -- what brought you in. Be as specific as possible about your joint pain and stiffness: when it hurts, where it hurts, how it feels, and whether your symptoms are interfering with your daily activities. Tell your doctor if you're taking any medications or nutritional supplements and whether they've affected your symptoms.
It may help to make a note of your symptoms before your appointment. For a printable list of your symptoms, take the free Rheumatoid Arthritis Assessment.
The Physical Examination
Your doctor will probably do a thorough exam to check your temperature, blood pressure, reflexes, muscle strength, lungs, skin, nails, eyes, mouth, and nose. And of course, your joints: Are they inflamed, swollen, tender, stiff? Is your range of movement limited?
Blood Tests
Blood tests can be used to help diagnose rheumatoid arthritis, but no single test is definitive. One test looks for rheumatoid factor, an antibody protein produced by your immune system. Rheumatoid factor is found in most -- but not all -- people with rheumatoid arthritis and may not be present in the early stages of the disease. It's also possible to have this antibody in your blood without having rheumatoid arthritis.
A second blood test measures the erythrocyte (red blood cell) sedimentation rate -- also called ESR or sed rate. This is likely to be higher than normal if rheumatoid arthritis is causing inflammation in your body.
And a third test looks for anti-CCP antibodies. Like rheumatoid factor, these antibodies are present in many, but not all, people with RA, and it's possible to have these antibodies without having rheumatoid arthritis.
Imaging
X-rays can be a useful tool for distinguishing between rheumatoid arthritis, osteoarthritis, and other conditions. However, early rheumatoid arthritis does not always appear on x-rays, because bone damage may not yet be visible. Magnetic resonance imaging (MRI), CT scans, and ultrasound may be better at identifying the early signs of rheumatoid arthritis.
If rheumatoid arthritis is diagnosed, this initial exam also sets a baseline, or reference point, for monitoring changes in your health and adjusting treatments accordingly.
