From the Guidelines
Laboratory tests for rheumatoid arthritis should include a minimal panel of C reactive protein (CRP)/erythrocyte sedimentation rate (ESR), full blood cell count, transaminase levels, renal function, and urine analysis, as recommended by the 2016 update of the EULAR recommendations for the management of early arthritis 1. When evaluating patients with rheumatoid arthritis, it is essential to consider the results of these laboratory tests in conjunction with clinical symptoms and history.
- The laboratory tests should be guided by the clinical examination and history taking, as stated in the 2016 update of the EULAR recommendations 1.
- In addition to the minimal laboratory panel, other tests such as rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) antibodies may be useful in establishing a diagnosis and prognosis of rheumatoid arthritis, as recommended by the multinational evidence-based recommendations on how to investigate and follow-up undifferentiated peripheral inflammatory arthritis 1.
- ESR and CRP should be performed at baseline and repeated when clinically relevant to assess disease activity and monitor treatment response 1.
- Regular monitoring of these markers is crucial to track disease progression and medication effectiveness, and some medications for RA require baseline and periodic lab monitoring for potential side effects, such as liver function tests for methotrexate or tuberculosis screening before starting biologics 1.
From the Research
Rheumatoid Arthritis Lab Work
- The diagnosis of rheumatoid arthritis (RA) can be supported by laboratory tests, including rheumatoid factor (RF), anti-citrullinated protein antibody (anti-CCP), C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR) 2, 3, 4, 5.
- The presence of RF, anti-CCP, or elevated CRP and ESR levels suggests a diagnosis of RA, especially in patients with inflammatory arthritis 2, 3.
- The sensitivity, specificity, and accuracy of these tests vary, with anti-CCP being more specific for the diagnosis of RA 4, 5.
- The combination of RF and anti-CCP antibody detection can improve the accuracy of RA diagnosis 4.
- Other laboratory tests, such as complete blood count with differential and assessment of renal and hepatic function, are also important in the initial evaluation of patients with suspected RA 2.
- Patients taking biologic agents should be tested for hepatitis B, hepatitis C, and tuberculosis 2.
Diagnostic Utility of Laboratory Tests
- The diagnostic utility of anti-CCP antibodies, RF, ESR, and CRP has been compared in patients with erosive and non-erosive RA 5.
- Anti-CCP antibodies have been found to have better diagnostic performance than other markers in patients with erosive RA 5.
- The presence of elevated anti-CCP antibody titers is associated with a higher frequency of erosions in RA patients 5.
Prognosis Prediction and Treatment
- The identification of autoantibodies, such as RF, anti-CCP, and anti-carbamylated protein antibodies, can facilitate early diagnosis and prognosis prediction in RA patients 6.
- These autoantibodies can precede the development of RA by years and have unique clinical relevance 6.
- The synergic effect of RF and anti-CCP can predict the development of RA and an erosive phenotype, while the additive value of anti-carbamylated protein antibodies is still controversial 6.