How is rheumatoid arthritis diagnosed? Part - II
Abnormal blood antibodies can be found in patients with RA. It is useful to know that a “rheumatoid factor” in 80% of patients and Citrulline antibody (also referred to as anti-citrulline antibody, anti-cyclic citrullinated peptide antibody, and anti-CCP) is present in most patients with rheumatoid arthritis. A traditional blood test will not reveal the presence of anti CCP, so a special blood test meant for the same has to be performed. Citrulline antibodies represent the earlier stages of rheumatoid arthritis. Another antibody called “the antinuclear antibody” (ANA) is also frequently found in patients with rheumatoid arthritis.
A blood test called the sedimentation rate (sed rate) is a measure of how fast red blood cells fall to the bottom of a test tube. It is used as a crude measure of the inflammation of the joints as it becomes faster during disease flares, and slower during remissions. Another blood test that is used to measure the degree of inflammation present in the body is the C-reactive protein. But these tests can also be abnormal in other systemic autoimmune and inflammatory conditions. Therefore, abnormalities in them alone are not enough for a positive diagnosis.
A negative Rheumatoid Factor does not rule out RA; rather, the arthritis is called seronegative. During the first year of illness, it is frequently negative. 80% of patients eventually turn seropositive in status.
But this test has very low specificity, so a new serological test has been developed now. It tests for the existence of so called anti-citrullinated protein antibodies (ACPA). Like RF, this test can detect approximately 80% of all RA patients, but is rarely positive in non-RA patients, giving it a specificity of around 98%. In addition, ACP antibodies can be often detected in early stages of the disease, or even before disease onset. Currently, most common test for ACP antibodies is the anti-CCP (cyclic citrulinated peptide) test.
Joint x-rays can be the standard ones that reveal bony erosions characteristic of later stage RA, or only swelling of soft tissues as seen in the premature levels of the disease. Joint x-rays assist in supervising the development of disease and joint damage over time. Bone scanning, a radioactive test method, can exhibit the inflamed joints.
The doctor reviews the history of symptoms, examines the joints for inflammation and deformity, the skin for rheumatoid nodules, and other parts of the body for inflammation. Certain blood and x-ray tests are often obtained. The diagnosis is based on the pattern of symptoms, the distribution of the inflamed joints, and the blood and x-ray findings. Several visits may be necessary before the doctor can be certain of the diagnosis.
Explore posts in the same categories: Rheumatoid Arthritis