From the Guidelines
Laboratory workup for suspected scleroderma should include antinuclear antibody (ANA) testing as the initial screening test, followed by specific autoantibodies including anti-centromere antibodies, anti-Scl-70/topoisomerase I antibodies, and anti-RNA polymerase III antibodies. The initial screening with ANA testing is crucial as it helps in identifying the presence of autoantibodies, which are a hallmark of autoimmune diseases like scleroderma 1.
Initial Screening and Autoantibodies
The specific autoantibodies to be tested include:
- Anti-centromere antibodies, which are associated with limited cutaneous scleroderma
- Anti-Scl-70/topoisomerase I antibodies, associated with diffuse cutaneous scleroderma
- Anti-RNA polymerase III antibodies, which are linked to rapid skin progression and an increased risk of renal crisis
Additional Laboratory Tests
Other laboratory tests that should be considered as part of the workup include:
- Complete blood count (CBC) to detect anemia of chronic disease or microangiopathic hemolytic anemia, especially in cases with renal crisis
- Comprehensive metabolic panel (CMP) to assess renal and hepatic function
- Urinalysis to detect proteinuria or hematuria, suggesting renal involvement
- Inflammatory markers like ESR and CRP, although they may be nonspecific
- Pulmonary function tests (PFTs) with DLCO measurement to evaluate for interstitial lung disease or pulmonary hypertension, as recommended by recent guidelines 1
- Creatine kinase and aldolase levels if there is concern for myositis overlap
Organ Involvement Screening
Screening for organ involvement is also crucial and should be guided by the patient's symptoms and disease subtype. This may include:
- Screening for pulmonary arterial hypertension (PAH) with echocardiography, pulmonary function testing, or NT-proBNP levels
- Screening for interstitial lung disease (ILD) with high-resolution CT of the lungs and pulmonary function testing
- Regular blood pressure checks and home blood pressure monitoring for early detection of scleroderma renal crisis, especially in patients with anti-RNAPIII antibodies or those with early diffuse cutaneous systemic sclerosis (dcSSc)
These tests are essential for establishing the diagnosis, determining the disease subtype, assessing organ involvement, and guiding treatment decisions, as emphasized in recent recommendations 1.
From the Research
Lab Workup for Scleroderma
When considering scleroderma in the differential diagnosis, the following lab workup is recommended:
- Antinuclear antibodies (ANA) testing: The presence of ANA is a key factor in the diagnosis of scleroderma 2, 3, 4, 5
- Anti-centromere antibodies: These antibodies are commonly found in patients with limited systemic scleroderma, also known as CREST syndrome 4, 5
- Anti-Scl-70 antibodies: These antibodies are specific for systemic sclerosis and are often associated with diffuse cutaneous involvement 3, 5
- Capillaroscopic analysis: Nailfold videocapillaroscopic (NVC) analysis can help distinguish between primary and secondary Raynaud's phenomenon and allow for early detection of scleroderma 6
- Other tests: Depending on the clinical presentation, other tests such as complete blood count, blood chemistry, and urinalysis may be ordered to rule out other conditions and assess organ involvement 3
Key Findings
- The presence of ANA, anti-centromere, and anti-Scl-70 antibodies can help support a diagnosis of scleroderma 2, 3, 4, 5
- The distribution of sclerosis and the presence of Raynaud's phenomenon are also important factors in the diagnosis of scleroderma 2, 3, 6
- Early detection and diagnosis of scleroderma are crucial for initiating appropriate treatment and improving patient outcomes 2, 3, 6