What tests should be ordered to evaluate and stage scleroderma?

Tests for Scleroderma

All patients with suspected or confirmed scleroderma should undergo autoantibody testing (ANA with specific SSc antibodies including anti-centromere, anti-topoisomerase 1/Scl-70, and anti-RNA polymerase III), baseline pulmonary function tests with DLCO, high-resolution chest CT, echocardiography, and regular blood pressure monitoring. 1

Initial Diagnostic Testing

Autoantibody Panel

• Antinuclear antibody (ANA) - present in >95% of systemic sclerosis patients
• SSc-specific antibodies 1:
  • Anti-centromere antibodies (associated with limited cutaneous SSc and PAH risk)
  • Anti-topoisomerase 1 (Scl-70) antibodies (higher frequency of ILD)
  • Anti-RNA polymerase III (anti-RNAPIII) antibodies (high risk of scleroderma renal crisis and malignancy)
  • Anti-U3-RNP, B23, Th/To, U1RNP (nucleolar antibodies associated with PAH)

Overlap Syndrome Screening

If clinical features suggest overlap with other connective tissue diseases, test for 1:

• Rheumatoid factor and anti-citrullinated peptide antibody (3% overlap with RA)
• Extractable nuclear antibodies: RNP, SSA/Ro, SSB/La, Smith, Jo1, PM/Scl-70, other myositis antibodies
• Complements C3, C4 and anti-DNA (for SLE overlap)

Organ-Specific Screening Tests

Pulmonary Assessment (Critical for Morbidity/Mortality)

For Interstitial Lung Disease 1, 2:

• Pulmonary function tests (spirometry, lung volumes, DLCO) - baseline and for monitoring
• High-resolution CT chest - especially in:
  • Anti-Scl-70 positive patients
  • Diffuse cutaneous SSc subset
  • Any unexplained dyspnea
• History and physical examination
• Chest radiography (less sensitive, not recommended as primary screening)

For Pulmonary Arterial Hypertension 1, 3:

• Echocardiography - primary screening tool 3
• DLCO - isolated decrease (especially <55% predicted) strongly predicts PAH development 3
• NT-proBNP - part of screening algorithms 1
• 6-minute walk distance - functional assessment 1
• ECG - baseline assessment 1

High-risk patients requiring enriched screening: longer disease duration, older age, low DLCO, limited cutaneous SSc with anti-centromere antibodies 1, 3

Renal Monitoring (Scleroderma Renal Crisis)

For early diffuse cutaneous SSc patients 1:

• Regular blood pressure checks - office and home monitoring
• Serum creatinine and electrolytes - baseline and periodic
• Highest risk: anti-RNAPIII positive, male sex, tendon friction rubs, rapidly progressive skin involvement, glucocorticoid use, active disease with other organ involvement

Cardiac Assessment

• Echocardiography - performed as part of PAH screening 1, 3
• ECG - if arrhythmias or heart failure suspected 1
• Additional cardiac workup if clinical suspicion warrants

Gastrointestinal Evaluation

• History and physical examination - 90% have GI involvement 1
• Alkaline phosphatase - screen for primary biliary cholangitis (8% of limited cutaneous SSc, especially anti-centromere positive) 1

Musculoskeletal Assessment

• Creatine kinase - if myositis/myopathy suspected (15% rule: 1 in 6 patients) 1
• Consider inflammatory arthritis workup if present

Skin Assessment

• Modified Rodnan skin score (mRSS) - clinical assessment of skin thickness at 17 anatomical sites (range 0-51) 1
• Biopsy only if diagnostic uncertainty or atypical features

Additional Baseline Tests

• Complete blood count
• Comprehensive metabolic panel (electrolytes, renal function, liver function)
• Thyroid function tests - if autoimmune thyroid disease suspected 1
• Urinalysis - baseline
• Bone density scan - if moderate suspicion of osteoporosis 1

Malignancy Screening

Enhanced screening if 1:

• Rapidly progressive diffuse cutaneous SSc with weight loss in elderly patient
• Anti-RNAPIII positive (increased malignancy risk)
• ILD present
• Cyclophosphamide or AHSCT exposure

Perform age-appropriate cancer screening per local guidelines plus periodic urine microscopy if cyclophosphamide exposure 1.

Monitoring Tests (After Diagnosis)

For SSc-ILD patients 2:

• Pulmonary function tests - primary monitoring tool
• HRCT chest - for those with SSc, frequency based on symptoms and PFT changes (not as often as PFTs due to radiation exposure)
• Ambulatory desaturation testing - to assess oxygen needs

Avoid routine monitoring with 2:

• Chest radiography
• 6-minute walk test distance alone
• Bronchoscopy (unless ruling out infection, sarcoidosis, lymphoma, or alveolar hemorrhage)
• Surgical lung biopsy (unless ruling out malignancy)

Critical Pitfalls to Avoid

1. Do not delay DLCO measurement - it predicts PAH development years before clinical manifestations 3
2. Do not rely on chest X-ray for ILD screening - HRCT is required 1, 2
3. Do not skip blood pressure monitoring in early diffuse cutaneous SSc - renal crisis can be catastrophic 1
4. In patients with Raynaud phenomenon, use ear or forehead oxygen saturation monitors instead of finger probes due to poor perfusion 2
5. Do not assume stable PFTs mean stable disease - HRCT may show progression with stable PFTs 2