From the Guidelines
The most appropriate laboratory tests to order for evaluating rheumatoid arthritis include rheumatoid factor (RF), anti-cyclic citrullinated peptide antibodies (anti-CCP), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), complete blood count (CBC), and comprehensive metabolic panel (CMP) 1. These tests are essential for diagnosing and monitoring rheumatoid arthritis, as they help assess disease activity, predict prognosis, and guide treatment decisions. Some key points to consider when ordering these tests include:
- RF and anti-CCP are specific markers for rheumatoid arthritis, with anti-CCP being more specific than RF 1
- ESR and CRP are non-specific inflammatory markers that help assess disease activity and monitor treatment response 1
- CBC can detect anemia of chronic disease, which is common in rheumatoid arthritis, while CMP evaluates liver and kidney function, which is important for monitoring potential medication side effects 1
- Additional tests may include antinuclear antibody (ANA) to rule out other autoimmune conditions, HLA-B27 for associated spondyloarthropathies, and synovial fluid analysis when joint effusion is present 1 It is essential to interpret these tests together with clinical findings, as no single test definitively diagnoses rheumatoid arthritis 1. Regular monitoring of these parameters helps guide treatment decisions and assess disease progression, ultimately improving patient outcomes and quality of life 1.
From the Research
Generalized Rheumatoid Labs to Order
The following laboratory tests are commonly ordered to diagnose and manage rheumatoid arthritis:
- Rheumatoid factor (RF) 2, 3, 4, 5
- Anti-cyclic citrullinated peptide (anti-CCP) antibodies 2, 3, 6, 4, 5
- Erythrocyte sedimentation rate (ESR) 2, 3, 4, 5
- C-reactive protein (CRP) 2, 3, 4, 5
- Complete blood count with differential 3
- Assessment of renal and hepatic function 3
- Tests for hepatitis B, hepatitis C, and tuberculosis in patients taking biologic agents 3
Laboratory Test Sensitivity and Specificity
The sensitivity and specificity of these laboratory tests vary:
- RF: 91.0% sensitivity, 74.4% specificity 4
- Anti-CCP antibodies: 88.0% sensitivity, 90.4% specificity 4
- Combination of RF and anti-CCP antibodies: 90.2% sensitivity, 83.3% specificity 4
- Anti-CCP antibodies are more specific than other parameters for the diagnosis of RA 4, 5
Diagnostic Utility
The diagnostic utility of these laboratory tests is as follows: