What four characteristics of RA help distinguish it from OA?
What constitutional symptoms may be seen in RA?
What are three characteristic physical findings in RA?
What five diseases may mimic RA?
Which serologic tests may be useful in the diagnosis of RA?
Discussion
What four characteristics of RA help distinguish it from OA?
Unlike patients with OA (noninflammatory), those with RA (inflammatory) experience morning stiffness lasting more than 30 minutes plus gel phenomenon (worse stiffness after rest);symmetric joint disease;characteristic bilateral synovitis of the hands and feet (PIPs, MCPs, and MTPs);and an intermittent or waxing and waning course.
What constitutional symptoms may be seen in RA?
Most patients experience generalized malaise or fatigue. Occasionally weight
loss, low-grade fever, sleep disturbance, or mild lymphadenopathy may be
present. These symptoms may be the end result of circulating inflammatory cytokines produced in the inflamed synovial tissue of the affected joints.
What are three characteristic physical findings in RA?
Physical findings encountered in the setting of RA may include swelling and warmth of one or more joints typically in a symmetric distribution, tenderness on palpation of the swollen joints, and the presence of nontender subcutaneous nodules (rheumatoid nodules) over the extensor surface of the forearm, Achilles tendon, and digits of the hands.
What five diseases may mimic RA?
RA may be mimicked by SLE and other CTDs such as mixed connective tissue disease(MCTD), scleroderma, and PMR; polyarticular gout or pseudogout; the arthritis of subacute bacterial endocarditis; the arthritis secondary to malignancy; and the seronegative spondyloarthropathies. The diagnosis of RA is based on the history, physical examination, and laboratory findings.
Which serologic tests may be useful in the diagnosis of RA?
RFs are autoantibodies directed against the Fc portion of IgG. In RA, RF has a sensitivity of approximately 80% and specificity of 80%. Therefore, RF is detected in approximately 80% of patients with RA but it is nonspecific and can be detected in many other disorders such as other CTDs and chronic viral or bacterial infections. Anti-CCP antibodies are directed against citrullinemodified arginine residues in a protein. In RA, anti-CCP antibodies have a sensitivity of 60% to 75% and a high specificity of 90% to 96%. Therefore, anti-CCP antibodies are usually detected only in RA. Patients with RA who have a positive RF and/or anti-CCP antibodies are at a higher risk of developing erosive joint destruction and debility. An elevated ESR or C-reactive protein (CRP) level suggests the presence of an acute inflammatory disease. A complete blood count may show an anemia of chronic (inflammatory) disease. ANAs are found in 30% of patients with RA, usually in a low titer with a negative ANA profile, and are of little diagnostic value.
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