From the Guidelines
The recommended workup for a patient suspected of having Systemic Lupus Erythematosus (SLE) should include a comprehensive clinical evaluation, laboratory testing, and sometimes imaging studies, with a focus on assessing disease activity, organ damage, and comorbidities, as outlined in the most recent guidelines 1.
Key Components of the Workup
- Initial laboratory tests should include complete blood count (CBC), comprehensive metabolic panel, urinalysis, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) 1.
- Specific autoantibody testing is crucial, particularly antinuclear antibody (ANA) testing, which is highly sensitive for SLE, and if positive, more specific antibody tests should follow, including anti-double-stranded DNA (anti-dsDNA), anti-Smith (anti-Sm), anti-SSA/Ro, anti-SSB/La, and anti-ribonucleoprotein (anti-RNP) antibodies 1.
- Complement levels (C3 and C4) should be measured, as they are often decreased in active SLE, and antiphospholipid antibodies (anticardiolipin antibodies, lupus anticoagulant, and anti-β2 glycoprotein I) should be assessed to evaluate for antiphospholipid syndrome 1.
Additional Considerations
- Depending on symptoms, chest X-ray, echocardiogram, or renal function tests may be indicated, and a skin or kidney biopsy might be necessary if organ involvement is suspected 1.
- The workup should also include an assessment of cardiovascular risk factors, osteoporosis, and cancer screening, as well as vaccination against infections, particularly in patients on immunosuppressive therapy 1.
Algorithm for Interpretation of Lab Tests
- The algorithm for the interpretation of lab tests in the management of patients with suspected SLE, as proposed by the expert panel 1, should be followed to guide the diagnosis and monitoring of the disease.
- This algorithm includes the use of ANA, anti-dsDNA, and other specific autoantibodies, as well as complement levels, to assess disease activity and guide treatment decisions 1.
From the Research
Recommended Workup for Systemic Lupus Erythematosus (SLE)
The workup for a patient suspected of having SLE involves several steps, including:
- Assessment of clinical symptoms, laboratory findings, and optional biopsy results 2
- Antinuclear antibody (ANA) testing, which is positive in nearly every case of SLE, but must be interpreted in the appropriate clinical context 3
- Measurement of clinical activity using scales such as the Systemic Lupus Activity Measure (SLAM) 4
- Laboratory tests, including complete blood cell count, erythrocyte sedimentation rate, urinalysis, 24-h protein and creatinine clearance, anti-DNA, C3 and C4 4
Key Features that Warrant ANA Testing
Key features that warrant ANA testing include:
- Unexplained multisystem inflammatory disease
- Symmetric joint pain with inflammatory features
- Photosensitive rash
- Cytopenias 3
Laboratory Abnormalities as Predictors of Disease Activity
Laboratory abnormalities, such as high levels of dsDNA and low complement levels, can predict disease activity and flares in patients with SLE 4
- Active nephritis and extrarenal manifestations correlate with high levels of dsDNA and low complement levels
- Asymptomatic patients with high dsDNA and low C3 levels have a higher risk of flare 4
Optional Biopsy Results
Optional biopsy results, such as renal biopsy, may be necessary to confirm the diagnosis of SLE and to assess the extent of organ involvement 2, 5