What are the initial steps for a rheumatoid workup?

Initial Rheumatoid Arthritis Workup

The initial workup for suspected rheumatoid arthritis requires identifying definite clinical synovitis in at least one joint not explained by another disease, followed by serologic testing (RF and anti-CCP), inflammatory markers (CRP and ESR), baseline imaging, and screening for contraindications to treatment. 1

Clinical Assessment

Joint Examination

• Examine for symmetric synovitis (swelling) in small joints, particularly metacarpophalangeal (MCP) joints, proximal interphalangeal (PIP) joints, wrists, and metatarsophalangeal (MTP) joints. 1, 2
• Large joints including shoulders, elbows, hips, knees, and ankles may also be affected. 1
• Distal interphalangeal (DIP) joints, first carpometacarpal joints, and first metatarsophalangeal joints are typically spared—their involvement suggests an alternative diagnosis. 1
• Perform a 28-joint count assessment for tenderness and swelling in PIPs, MCPs, wrists, elbows, shoulders, and knees. 1

Key Clinical Features

• Morning stiffness lasting at least 1 hour before maximal improvement is characteristic of RA. 2
• Assess for constitutional symptoms including fatigue, fever, weight loss, and malaise. 2
• Evaluate for extra-articular manifestations such as rheumatoid nodules. 2

Laboratory Testing

Serologic Studies

• Anti-citrullinated protein antibody (ACPA) testing: high specificity (90%) with moderate sensitivity (60%). 1
• Rheumatoid factor (RF) testing: lower specificity (70%) with similar sensitivity to ACPA. 1
• Remember that seronegative RA accounts for 20-30% of cases—negative RF does not exclude RA. 1

Inflammatory Markers

• C-reactive protein (CRP) is preferred over ESR as it is more reliable and not age-dependent. 1
• Erythrocyte sedimentation rate (ESR) should be measured at baseline for diagnostic and prognostic purposes. 1
• Do not dismiss the diagnosis based on normal inflammatory markers—ESR and CRP can be normal even in active disease. 1

Additional Laboratory Tests

• Complete blood count with differential to assess for cytopenias. 1
• Comprehensive metabolic panel including liver function tests, renal function, glucose, and urate levels. 1
• Urinalysis as part of the standard workup. 1
• Antinuclear antibodies (ANA) can be used to screen for other connective tissue diseases if the diagnosis is uncertain. 1

Pre-Treatment Screening

• Screen for hepatitis B, hepatitis C, and tuberculosis before starting biologic agents or methotrexate. 1, 3

Imaging Studies

Baseline Radiography

• Obtain bilateral hand, wrist, and foot X-rays at baseline to monitor structural damage progression. 1
• Conventional radiography hallmarks include periarticular osteopenia, uniform joint space narrowing, and osseous erosions. 1
• Erosions predict RA diagnosis and disease persistence. 1

Advanced Imaging (When Indicated)

• Ultrasound is superior to clinical examination for detecting inflammation and structural damage, and can detect synovitis that predicts disease progression. 1
• Power Doppler ultrasound is useful when patients with early arthritis do not meet the 2010 ACR/EULAR criteria. 1
• MRI with IV contrast is more sensitive than ultrasound in early stages, detecting bone marrow edema (osteitis) which is the best single predictor of future disease progression. 1

Diagnostic Scoring System

2010 ACR/EULAR Classification Criteria

A score of ≥6/10 points is needed for definite RA classification. 1

Joint Involvement Scoring:

• 1 large joint = 0 points
• 2-10 large joints = 1 point
• 1-3 small joints = 2 points
• 4-10 small joints = 3 points

• 10 joints = 5 points 1

Serology Scoring:

• Negative RF and ACPA = 0 points
• Low positive RF or ACPA = 2 points
• High positive RF or ACPA = 3 points 1

Acute Phase Reactants:

• Normal CRP and ESR = 0 points
• Abnormal CRP or ESR = 1 point 1

Symptom Duration:

• <6 weeks = 0 points
• ≥6 weeks = 1 point 1

Critical Pitfalls to Avoid

• Do not delay treatment waiting for positive serology—seronegative RA is common and has similar prognosis. 1
• Do not dismiss the diagnosis based on normal ESR/CRP—acute phase reactants are poor predictors of RA. 1
• If the initial score is <6/10, consider advanced imaging (ultrasound or MRI) to detect subclinical synovitis and arrange follow-up evaluation as patients may develop additional features over time. 1

Differential Diagnosis Considerations

Exclude psoriatic arthritis, gout, and hemochromatosis, which can present with similar symptoms. 1