Basic Rheumatology Panel Laboratory Tests
A basic rheumatology panel should include C-reactive protein (CRP)/erythrocyte sedimentation rate (ESR), complete blood count, liver transaminase levels, renal function, and autoantibody testing including rheumatoid factor (RF) and anti-citrullinated peptide antibodies (ACPA). 1
Core Components of a Basic Rheumatology Panel
Inflammatory Markers
- C-reactive protein (CRP) - Acute phase reactant that measures inflammation
- Erythrocyte sedimentation rate (ESR) - Non-specific marker of inflammation
- These should be performed at baseline and repeated when clinically relevant 1
Complete Blood Count (CBC)
- Full blood cell count to assess for anemia, leukopenia, or thrombocytopenia
- CBC-derived parameters like neutrophil-to-lymphocyte ratio (NLR) can provide additional information about disease activity 2
Autoantibody Testing
- Rheumatoid factor (RF) - Sensitivity ~91%, specificity ~74% for rheumatoid arthritis 3
- Anti-citrullinated peptide antibodies (ACPA/anti-CCP) - Higher specificity (~90%) for rheumatoid arthritis 3
- Antinuclear antibodies (ANA) - For screening connective tissue diseases 1
Organ Function Tests
- Liver function tests - Transaminase levels (AST, ALT)
- Renal function tests - Creatinine, BUN
- Urine analysis - To assess for renal involvement 1
Additional Tests Based on Clinical Suspicion
For Suspected Systemic Sclerosis
- Anti-Scl-70/topoisomerase-1
- Anti-centromere antibodies
- Anti-RNA polymerase III 1
For Suspected Sjögren's Syndrome
- Anti-SSA/Ro
- Anti-SSB/La 1
For Suspected Myositis
- Creatine kinase (CK)
- Aldolase
- Myositis-specific antibodies (if available) 1
For Suspected Vasculitis
- Anti-neutrophil cytoplasmic antibodies (ANCA) 1
Monitoring Recommendations
For patients on disease-modifying antirheumatic drugs (DMARDs), follow-up laboratory monitoring should be conducted at these intervals 1:
| Therapeutic agents | <3 months | 3-6 months | >6 months |
|---|---|---|---|
| Methotrexate | 2-4 weeks | 8-12 weeks | 12 weeks |
| Leflunomide | 2-4 weeks | 8-12 weeks | 12 weeks |
| Sulfasalazine | 2-4 weeks | 8-12 weeks | 12 weeks |
| Hydroxychloroquine | None after baseline | None | None |
Clinical Utility
The combination of RF and anti-CCP antibody testing provides better diagnostic accuracy (89.5%) than either test alone 3. When discordance occurs between ESR and CRP (approximately 28% of cases), CRP is generally a better measure of disease activity, while ESR may be influenced by immunoglobulins, RF, and hemoglobin levels 4.
Anti-CCP antibodies have demonstrated superior diagnostic performance for erosive rheumatoid arthritis compared to other markers, with significantly higher titers found in patients with erosive disease 5.
Remember that laboratory tests should support clinical findings from history and physical examination, and in some cases, can be used to monitor disease activity 6.