Rheumatoid Arthritis Diagnosis
With dozens of different types of arthritis, pinpointing which kind you have – or whether you have it at all – can be a tough task for doctors. A rheumatoid arthritis (RA) diagnosis may involve seeing a specialist, along with blood and imaging tests. Your family doctor may refer you to a rheumatologist, a doctor who is an arthritis expert.
Medical history and symptoms
The first thing your doctor will do is learn more about your medical history and symptoms. They will examine you and ask you questions like:1
- Could an injury or illness be causing your pain?
- Does anyone in your family have arthritis or another rheumatic disease?
- Do you take any medicines? If so, which ones?
- What are your symptoms? Do you have pain, stiffness, swelling, or trouble moving?
- Where do you feel these symptoms?
- How long have you been in pain?
- How long does each round of pain continue?
- What does your pain feel like? Is it sharp, dull, pulsing?
- Rate your pain on a scale of 1 to 10.
- Does anything make the pain feel better or worse?
Blood tests to diagnose rheumatoid arthritis
There are several blood tests to help your doctor make a rheumatoid arthritis diagnosis:1-4
Erythrocyte sedimentation rate (ESR or sed rate)
This test shows whether you have inflammation in your body.
Complete blood count (CBC)
This test measures the red blood cells, white blood cells, and platelets in your blood. A low red blood cell count (anemia) can be a symptom of RA or a side effect of some medicines.
C-reactive protein (CRP)
If you have inflammation, this protein will show up in higher levels in your blood.
Rheumatoid factor (RF)
Rheumatoid factors are a type of protein made by your immune system. High RF blood levels mean the protein is attacking healthy tissue, and you may have RA. A positive RF test is standard in RA, with about 80 percent of people with the illness testing positive.
Cyclic citrullinated peptides (CCP) antibodies (anti-CCP)
CCP antibodies are proteins that target healthy joint tissue. They are also a red flag for RA. About 60 to 70 percent of people with RA have a positive CCP antibody test. The term CCP antibodies is also known as anti-CCP antibodies.
Imaging tests to diagnose rheumatoid arthritis
Your doctor may also order one or more imaging tests to figure out if you have RA. These may include:1
RA causes changes to the joints and bones, which an X-ray might reveal. In the early stages of RA, X-rays cannot reveal damage from RA.
Using sound waves, an ultrasound shows features of the synovial tissue, tendons, ligaments, and bones.
Magnetic resonance imaging (MRI)
An MRI uses a magnetic field and computer-generated radio waves to produce detailed images of the muscles, ligaments, and cartilage.
This test also shows any changes to the joint that signal RA or other illnesses. Your doctor will make a small cut in your skin, then work in a thin tube with a light and camera. The camera displays images on a screen.
How your doctor can tell if you have rheumatoid arthritis
After testing is finished, your doctor will decide if you have RA. But before that, they will need to rule out other conditions that can mimic RA. It is important to rule out these other diagnoses because they often require a different treatment strategy. These conditions include:5
- Osteoarthritis, a type of arthritis in which the protective tissue at the ends of bones begin to break down
- Psoriatic arthritis, a type of inflammatory arthritis that is often associated with psoriasis
- Polymalagia rheumatica, a disorder that causes inflamed muscles around the shoulders and hips
- Infectious arthritis, an infection in the joint
In order to rule out these other diagnoses, your doctor will use a set of RA criteria established by scientific study and real-world practice. Here are the signs, symptoms, and test results your doctor will look for:2
- At least 2 joints impacted by inflammatory arthritis, including the shoulders, elbows, hips, knees, and ankles
- Smaller joints affected by inflammatory arthritis
- A positive result on a rheumatoid factor or CCP antibody test
- Higher CRP or sed rate levels
- Symptoms for 6 weeks or longer
Keep in mind that you may not meet all of these criteria, but your doctor could still diagnose you with RA.2