What blood tests are used to diagnose Rheumatoid Arthritis (RA)?

From the Guidelines

Blood work for rheumatoid arthritis should include rheumatoid factor (RF), anti-cyclic citrullinated peptide (anti-CCP) antibodies, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) to diagnose and monitor the condition. These tests are essential for assessing disease activity and guiding treatment decisions 1. The EULAR recommendations for the management of early arthritis emphasize the importance of measuring ESR or CRP, levels of rheumatoid factor and anti-CCP antibodies, and radiographic erosions in patients presenting with early arthritis 1. Additionally, a complete blood count (CBC) may be performed to check for anemia, which is common in rheumatoid arthritis patients. Other tests, such as antinuclear antibody (ANA) test, may be used to rule out other autoimmune conditions. It is crucial to consider clinical symptoms, physical examination findings, and imaging studies alongside blood test results to accurately diagnose and manage rheumatoid arthritis. The American College of Rheumatology recommends using disease activity measures, such as the CDAI, DAS28, PAS, PAS-II, RAPID-3, and SDAI, to monitor disease activity and adjust treatment accordingly 1.

From the Research

Blood Work for Rheumatoid Arthritis

• The following blood tests are commonly used to diagnose rheumatoid arthritis:
  • Rheumatoid factor (RF) 2, 3, 4, 5
  • Anti-citrullinated protein antibody (anti-CCP) 2, 3, 4, 5
  • C-reactive protein (CRP) 2, 3, 4, 6
  • Erythrocyte sedimentation rate (ESR) 2, 3, 4
• These tests can help identify inflammation and autoimmune activity in the body, which are characteristic of rheumatoid arthritis 2, 3, 4, 5, 6
• A complete blood count (CBC) with differential and assessment of renal and hepatic function may also be included in the initial laboratory evaluation 3
• The presence of RF and/or anti-CCP antibody, elevated CRP level, or elevated ESR is consistent with a diagnosis of rheumatoid arthritis 2, 3, 4

Diagnostic Criteria

• The diagnosis of rheumatoid arthritis is based on a combination of clinical criteria, including joint swelling and inflammation, and laboratory test results 2, 3, 6
• The American College of Rheumatology and European Alliance of Associations for Rheumatology recommend a treat-to-target approach, including rapid interventions to reduce disease activity and achieve remission 6

Laboratory Test Results

• The sensitivity, specificity, and accuracy of RF, anti-CCP antibody, CRP, and ESR in the diagnosis of rheumatoid arthritis have been studied, with anti-CCP antibody being more specific than the other parameters 4
• Combined detection of these parameters is beneficial when confirming a diagnosis of rheumatoid arthritis 4