Rheumatoid arthritis is a chronic autoimmune disorder characterized by inflammation of the joints and often other body sites. A variety of tests are used for diagnosis and monitoring of the disease, including C-reactive protein, or CRP. CRP levels reflect the extent of inflammation in your body, aiding in the evaluation of the severity of rheumatoid arthritis and its response to treatment.
Rheumatoid Arthritis
Rheumatoid arthritis is classified as an autoimmune disease, meaning your body's own defense system is mistakenly attacking normal components of the joints and other body sites. The disease is more common in women than men, and can occur at any age, according to MedlinePlus, a publication of the National Institutes of Health. Rheumatoid arthritis usually starts with fatigue, mild fevers and weakness, followed eventually by joint pain. Affected joints are classically stiff in the morning, and can be warm, tender and painful on both sides of the body. Any joint can be involved, most commonly those of the upper and lower limbs, the jaw and the neck. Joint destruction can begin within one or two years and inflammation can develop in other areas such as the lungs, eyes and skin.
Diagnosis and Monitoring
The best diagnostic blood test for rheumatoid arthritis is the anti-CCP test, which detects a circulating antibody rarely present except in rheumatoid arthritis patients, according to the National Rheumatoid Arthritis Society of the UK. Only about 60 percent of patients will be positive for anti-CCP, so other tests are often necessary to reach a diagnosis. An older blood test called rheumatoid factor is positive in roughly 75 percent of rheumatoid arthritis patients, but can also be positive with other conditions making it less specific for diagnosis. Radiologic examination often shows characteristic joint changes, helping in the diagnosis. A complete blood count, erythrocyte sedimentation rate and CRP are also commonly performed to assess inflammation, but are more useful for monitoring the activity level of rheumatoid arthritis over time.
CRP in Rheumatoid Arthritis
C-reactive protein is an acute phase reactant, one of several proteins in your body that increase in response to tissue injury, infection, cancer and inflammation. CRP is produced by the liver, rapidly increasing when inflammation is present and rapidly decreasing as inflammation improves. This makes CRP a good monitoring tool for disease activity and treatment response in rheumatoid arthritis. CRP levels are usually elevated in untreated rheumatoid arthritis, the degree of elevation correlating roughly with the severity of inflammation. By measuring CRP levels after treatment is started, your health care provider can assess the efficacy of treatment by how far and how rapidly the CRP levels fall.
Treatment and Prognosis
A variety of treatments are available for rheumatoid arthritis depending on the stage of the disease. Disease modifying antirheumatic drugs, or DMARDs, such as methotrexate are the treatment of choice, along with anti-inflammatory medication, physical therapy and rest. Corticosteroids might be used to reduce swelling and inflammation in the short term, as well as other drugs to modify your body's immune response. Surgery can relieve some causes of joint pain, swelling and repair joint deformities when necessary. The prognosis of rheumatoid arthritis varies from person to person, but even with optimal care approximately 10 percent of people will eventually develop severe disabilities related to joint damage.
