Rheumatoid Arthritis
How is it diagnosed?
Diagnosing rheumatoid arthritis is a process. There isn’t a sure-fire test that can tell you positively that you have RA. Instead your doctor relies on a number of tools to help him determine the best treatment for your symptoms.
A diagnosis will be made from a medical history, a physical exam, lab tests and X-rays.
Medical History
Medical history probably is your doctor’s best tool for diagnosing rheumatoid arthritis. The more your doctor knows about you, the faster and better he will be able to diagnose your condition and determine the best treatment for you. Taking a medical history is the first line to finding out if you have rheumatoid arthritis. What you tell him will allow him to determine if RA should be considered a possible diagnosis or if he should look in another direction.
Following is a list of questions your doctor might ask in a medical history:
- Do you have joint pain in many joints?
- Does the pain occur symmetrically – that is, do the same joints on both sides of your body hurt at the same time? Or is the pain one-sided?
- Do you have stiffness in the morning?
- When is the pain most severe?
- Do you have pain in your hands, wrists and/or feet?
- If you have pain in your hands, which joints hurt the most?
- Have you had periods of feeling weak and uncomfortable all over? Do you feel fatigued?
You may have to answer these questions at every office visit so your doctor can best evaluate your pain and functionality status. You also might find yourself taking a self-report questionnaire. These are developed to help the doctor assess the impact of RA on your daily life. Two of the most common are the Health Assessment Questionnaire (HAQ) and the Arthritis Impact Measurement Scales (AIMS).
Physical Exam
Your doctor also will perform a physical exam to determine diagnosis and at most following office visits. He will be looking for common features reported in RA, including:
- Joint swelling
- Joint tenderness
- Loss of motion in your joints
- Joint malalignment
- Signs of rheumatoid arthritis in other organs, including your skin, lungs and eyes.
Lab Tests
While there is no one test to confirm whether or not you have rheumatoid arthritis, your doctor may use several different tests and imaging studies to help make a diagnosis. The most commonly used tests are listed below, but not all doctors will use every test and some may use tests not described. You should feel free to fully question your doctor for any tests he or she orders so you understand what it is measuring and why. Most tests ordered to help with diagnosis will only have to be taken once. Tests designed to measure improvement or to check for drug side effects may need to be repeated regularly. For additional information about lab tests, visit Guide to Lab Tests.
Complete Blood Count
There are three types of cells in your blood: red blood cells, which carry oxygen to tissues; white blood cells, which help fight infections; and platelets, which help the blood clot. Each may be tested to check for abnormalities that might exist or to monitor side effects of drugs and check progress.
People with rheumatoid arthritis often have a low red blood count, signally anemia, a common problem for people with RA. Anemia can contribute to feelings of fatigue. People with more aggressive disease tend to have more severe anemia.
White blood cells may be high, signaling that infection is present in your body. A low white blood cell count could suggest Felty’s syndrome, a complication of RA, or may be caused by some medications.
Your platelet count is elevated when you have inflammation present in the body. It can also be lowered by certain drugs.
If you take nonsteroidal anti-inflammatory drugs (NSAIDs), your platelet and white blood cell count will be monitored every six months. People taking disease-modifying antirhuematic drugs (DMARDs), will be checked every two to 12 weeks.
Erythrocyte Sedimentation Rate (ESR or sed rate)
The erythrocyte sedimentation rate (ESR) measures the speed at which red blood cells fall to the bottom of a test tube. The more rapidly your red blood cells drop, the more inflammation is present in the body. A high sed rate indicates inflammation and the higher it is, the more severe the RA is. Your sed rate will be checked frequently to see if treatment is working successfully.
You should note that only about 60 percent people with RA have an elevated sed rate. Because your treatment is based primarily on clinical symptoms, a normal sed rate doesn’t mean that you are cured and no longer need treatment for RA.
C-Reactive Protein
C-reactive protein (CRP) is found in the body and is elevated when inflammation is found in the body. The higher the level of CRP the more disease activity is involved. Although ESR and CRP reflect similar degrees of inflammation, sometimes one will be raised when the other isn’t. This test may be repeated regularly to monitor your inflammation and your response to medication.
Rheumatoid Factor
Approximately 70 to 80 percent of people with rheumatoid factor (RF) also have rheumatoid arthritis. It is tested by measuring the amount of RF in your body. The higher the amount of RH present in the body, the more active and severe your disease is.
Some people with RA do not have RF in their blood. They are called “seronegative.” People with RF in there blood are called “seropositive.”
Antinuclear Antibodies (ANA)
This test detects a group of autoantibodies (antibodies against self), which is seen in about 30 to 40 percent of people with RA. Although it commonly is used as a screening tool, ANA testing isn't used as a diagnostic tool because many people without RA or with other diseases can have ANAs.
Imaging Studies
Radiographs (X-rays)
Your doctor may take X-rays of your bones and joints upon diagnosis with RA to provide a valuable baseline for comparison with later X-rays. They show the swelling of the soft tissues and the loss of bone density around the joints – the result of your reduced activity and inflammation. As your disease progresses, your X-rays can show small holes or erosions near the ends of bone s and narrowing of the joint space due to loss of cartilage. Doctors used to wait until the appearance of erosion before beginning aggressive treatment of RA. Now it is widely believed that it is better to treat aggressively before the development of erosion.
Magnetic Resonance Imaging (MRI)
A MRI can detect early inflammation before it is visible on an X-ray, and are particularly good at pinpointing synovitis (inflammation of the lining of the joint)
Joint Ultrasound
Joint ultrasound is a much less expensive way to look for joint inflammation before X-rays show damage. Although not currently used often, this procedure may gain wider use over the next few years as doctors increase their efforts to document early evidence of the disease.
Bone Densitometry (DEXA)
Bone densitometry is an important imaging study for measuring bone density, used primarily to detect osteoporosis. Osteoporosis may be especially severe in people with RA due to joint immobilization, the inflammatory response itself and the use of certain therapies (such as glucocorticoids) that may hasten bone loss. Some doctors suggest that a bone density test should be part of the evaluation and monitoring of all people with RA, particularly for women after menopause.
