What tests should be ordered for a patient with multiple joint pain for one year?

Diagnostic Workup for Multiple Joint Pain of One Year Duration

For a patient with multiple joint pain persisting for one year, a comprehensive diagnostic workup should include autoimmune blood panel, inflammatory markers, radiographic imaging, and targeted testing based on clinical presentation to identify the underlying cause and guide appropriate treatment. 1

Initial Laboratory Testing

• Inflammatory Markers:

  • Erythrocyte Sedimentation Rate (ESR) and C-reactive Protein (CRP) 1, 2
    • Essential baseline tests for diagnosis and prognosis of inflammatory arthritis
    • Should be repeated when clinically relevant to monitor disease activity
    • Note: ESR has a longer half-life than CRP, making it more useful for chronic conditions, while CRP is more responsive to acute changes 3

• Autoantibody Testing:

  • Rheumatoid Factor (RF) and Anti-Citrullinated Protein Antibodies (ACPA) 1, 2
    • Strong predictors of rheumatoid arthritis diagnosis and prognosis
    • High specificity (ACPA: 95-98%, RF: 78-85%) 2
    • Negative tests do not exclude progression to inflammatory arthritis
  • Additional autoantibody tests if systemic inflammatory disorders are suspected:
    • Antinuclear Antibody (ANA) for suspected connective tissue diseases 2
    • HLA-B27 testing if symptoms suggest reactive arthritis or spondyloarthritis 1

• Complete Blood Count (CBC) with differential 4

  • To evaluate for anemia, leukocytosis, thrombocytosis which may indicate inflammatory disease

• Basic Metabolic Panel and Liver Function Tests 4

  • To assess renal and hepatic function (important for treatment planning)

Imaging Studies

• Plain Radiographs:

  • X-rays of affected joints at baseline 1
  • X-rays of hands, wrists, and feet should be performed even if not the primary complaint sites 1
    • Presence of erosions is predictive for development of rheumatoid arthritis
    • Baseline radiographs help assess future progression
  • Consider pelvic/sacroiliac joint x-rays if spondyloarthritis is suspected, particularly in RF and ACPA-negative patients 1

• Advanced Imaging (when indicated):

  • MRI of hands and wrists if rheumatoid arthritis is suspected but diagnosis is uncertain 1
  • Ultrasound to detect synovitis if clinical examination is equivocal 1, 5
    • Not recommended for routine use but can help detect early inflammatory changes

Additional Testing Based on Clinical Presentation

• Joint Aspiration and Synovial Fluid Analysis 1

  • Indicated for:
    • Persistent monoarthritis
    • Suspected septic arthritis
    • Suspected crystal arthropathy (gout, pseudogout)
  • Analysis should include:
    • Cell count and differential
    • Crystal examination
    • Culture and Gram stain

• Testing for Infectious Causes:

  • Consider hepatitis B and C testing if viral arthritis suspected or if planning immunosuppressive therapy 4
  • Tuberculosis testing prior to biologic therapy 4

Clinical Assessment Documentation

Document key predictors of persistent inflammatory arthritis 1:

• Disease duration ≥6 weeks
• Morning stiffness >30 minutes
• Functional impairment
• Small joint involvement
• Involvement of ≥3 joints
• ACPA and/or RF positivity
• Presence of radiographic erosions

Common Pitfalls to Avoid

1. Overlooking osteoarthritis as a cause of polyarticular pain, especially in older patients 5

   • Osteoarthritis can also present with elevated inflammatory markers, particularly in advanced disease 6

2. Relying solely on laboratory tests for diagnosis

   • Negative RF and ACPA do not exclude inflammatory arthritis 1
   • Clinical assessment remains crucial for diagnosis

3. Delaying appropriate testing

   • Early diagnosis allows for earlier treatment with disease-modifying agents 4
   • Radiographic damage may occur early in disease course

4. Failing to consider non-rheumatologic causes

   • All possible causes of arthritis should be considered (autoimmune, infectious, malignancy, metabolic, etc.) 1

By following this systematic approach to testing, clinicians can efficiently diagnose the cause of multiple joint pain and initiate appropriate treatment to prevent joint damage and disability.