Fast Five Quiz: Rheumatoid Arthritis Workup

Herbert S. Diamond, MD

Disclosures

June 10, 2020

Patients with RA and SLE often have similar signs and symptoms during the early stages of disease onset, including joint swelling, morning stiffness of the joints, fatigue, low-grade fever, and malaise. Patients with early SLE and patients with RA may have a seropositive test result for RF and/or anti-ACC antibodies. Moreover, although patients with SLE tend to have high ANA levels, as previously noted, a positive ANA test result occurs in patients with other conditions, including RA. RA may be differentiated from SLE through additional laboratory and imaging studies, physical examination findings (eg, malar rash, alopecia associated with SLE), and the presence of other symptoms such as photosensitivity. The EULAR/ACR Classification Criteria for Systemic Lupus Erythematous and ACR/EULAR Classification Criteria for Rheumatoid Arthritis are not intended for diagnosis but may help clinicians in distinguishing between SLE and RA.

Patients with Lyme disease may also have signs and symptoms similar to early-stage RA and have a seropositive test result for RF, but a careful history and physical examination, an enzyme-linked immunoassay test to detect Borrelia burgdorferi, and imaging studies can help physicians distinguish Lyme disease from RA.

Although patients with osteoarthritis (OA) may have similar symptoms to patients with early-stage RA, such as joint pain and stiffness, unlike patients with RA, there are no abnormalities on the standard laboratory examination associated with OA. Clinicians should nevertheless be aware that a positive test result for RF in patients with OA (typically, a low titer) may be seen in healthy patients and is more frequently seen in older patients. As in RA, elevated levels of some cartilage and bone turnover fragments may be found.

Symptoms of arthritis and fever associated with rheumatic fever may mimic early-stage RA; however, other signs and symptoms differ, and unlike patients with RA, laboratory studies in patients with rheumatic fever reveal an elevated antistreptolysin O titer.

Learn more about the differential diagnoses for RA.

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