Exams and Tests

On hearing your symptoms, your health-care professional will suspect that you have rheumatoid arthritis or another type of arthritis or rheumatic disease. The diagnosis doesn't end there, though. It is very important to know exactly which type of arthritis you have, because the treatment and outlook for each type may differ.

Your health-care professional will conduct a thorough interview and physical examination to try to pinpoint the cause of the symptoms. You will be asked about your symptoms, about other medical problems now and in the past, about your family's medical problems, about the medications you take, and about your habits and lifestyle.

There is no single test that can confirm the diagnosis of rheumatoid arthritis. Your health-care professional will use the results of your interview and physical examination, lab tests, and imaging studies such as X-rays to determine whether you have rheumatoid arthritis. At any time in the process of making the diagnosis or treating the condition, your primary-care provider may refer you to a rheumatologist (a specialist in diagnosing and treating rheumatoid arthritis).

Lab tests: Your health-care professional may suggest any of the following tests:

• Complete blood count: This test measures how many of each type of blood cell are in your blood. This will show anemia as well as abnormalities in white blood cell counts or platelet counts that could be associated with rheumatoid arthritis.



• Markers of inflammation: These include measures such as erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). Levels of both of these are usually high in rheumatoid arthritis and may be good indicators of the extent of disease activity at any given time.



• Other blood tests: Levels of electrolytes (such as calcium, magnesium, and potassium) and proteins may be tested. Kidney and liver functions also may be checked and monitored while taking medications.



• Immunologic tests: Levels of rheumatoid factor (RF), antinuclear antibodies (ANA), and possibly other antibodies (anti-RA33, anti-CCP) may be checked. The majority of people have a positive RF result during periods of active disease. A positive ANA result indicates an unusually active immune system. About 40% of people with rheumatoid arthritis have a positive ANA result. In the first few months of onset of rheumatoid arthritis, these immunologic tests may be negative, and, in some patients, they are always negative.

Synovial fluid analysis: The tissue that lines the joint (synovium) produces fluid that helps lubricate and protect joints. Like blood, this fluid may be abnormal in quality and excessive quantity from rheumatoid arthritis. It may reveal characteristic signs of inflammation that point to rheumatoid arthritis, such as an elevated number of white blood cells. A sample of this fluid is withdrawn from a joint (usually the knee) through a needle in a procedure called arthrocentesis, or joint aspiration. The fluid is examined and analyzed for signs of inflammation.

Imaging studies: X-rays and sometimes other imaging studies often are used to detect damage to the joints.

• X-rays: X-rays may be taken of sites where symptoms or signs occur. Early in rheumatoid arthritis, the X-ray may be normal or show only soft-tissue swelling, but damage can still be occurring. Over time, the usual finding is erosion of the bony part of the joint. These changes are distinguishable from changes seen with other types of arthritis such as osteoarthritis.



• MRI: MRI may allow earlier detection of bone erosion than X-rays.



• Ultrasound: Ultrasound uses high-frequency sound waves to take pictures of structures inside the body. It can be used to examine and to detect abnormal collections of fluid in the soft tissues around joints. The abnormal collection of joint fluid is referred to as a joint effusion.



• Bone scanning: In this test, a special image of the entire skeleton is obtained after a small amount of radioactive isotope is injected into a vein. Diseased or damaged bone takes up the radioisotope in a different way than healthy bone and gives a characteristic picture. This technique may be used to detect inflammatory changes in bone.



• Densitometry: This scan detects changes in the thickness of bone that may indicate osteoporosis.



• Arthroscopy: A small scope, a long narrow tube with a light and a camera on the end, is used to examine the inside of the joint. The scope is inserted through a small incision in the skin. The camera transmits pictures to a video monitor, allowing the doctor to detect signs of rheumatoid arthritis or other joint disease. This test is not always necessary.

Classification

The American College of Rheumatology has developed a system for classifying rheumatoid arthritis. This system helps medical professionals determine the severity of your rheumatoid arthritis.

Stage I

• no damage seen on X-rays, although there may be signs of bone thinning

Stage II

• on X-ray, evidence of bone thinning around a joint with or without slight bone damage



• slight cartilage damage possible



• joint mobility may be limited; no joint deformities observed



• atrophy of adjacent muscle



• abnormalities of soft tissue around joint possible

Stage III

• on X-ray, evidence of cartilage and bone damage and bone thinning around the joint



• joint deformity without permanent stiffening or fixation of the joint



• extensive muscle atrophy



• abnormalities of soft tissue around joint possible

Stage IV

• on X-ray, evidence of cartilage and bone damage and osteoporosis around joint



• joint deformity with permanent stiffening or fixation of the joint (ankylosis)



• extensive muscle atrophy



• abnormalities of soft tissue around joint possible

Rheumatologists also classify the functional status of persons with rheumatoid arthritis as follows:

• Class I: completely able to perform usual activities of daily living



• Class II: able to perform usual self-care and work activities but limited in activities outside of work (such as playing sports, household chores)



• Class II: able to perform usual self-care activities but limited in work and other activities



• Class IV: limited in ability to perform usual self-care, work, and other activities

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Rheumatoid Arthritis - Early Symptoms

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