What is the workup for systemic lupus erythematosus (SLE)?

Workup for Systemic Lupus Erythematosus (SLE)

The workup for systemic lupus erythematosus must include laboratory testing for antinuclear antibody (ANA), anti-double-stranded DNA (anti-dsDNA), anti-Smith (anti-Sm) antibodies, complement levels (C3, C4), complete blood count, comprehensive metabolic panel, urinalysis, and assessment of organ-specific manifestations based on clinical presentation. 1

Initial Laboratory Evaluation

Essential Laboratory Tests

• Antinuclear antibody (ANA) testing - primary screening test 1, 2
• Anti-double-stranded DNA (anti-dsDNA) antibodies 1
• Anti-Smith (anti-Sm) antibodies 1
• Complement levels (C3, C4) 3, 1
• Complete blood count with differential (to assess for cytopenias) 1
• Comprehensive metabolic panel (liver and kidney function) 1
• Urinalysis with microscopy and urine protein-to-creatinine ratio 1
• Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) 1

Additional Immunologic Testing

• Antiphospholipid antibodies (anticardiolipin, lupus anticoagulant, anti-β2 glycoprotein I) 3, 1
• Anti-Ro/SSA and anti-La/SSB antibodies (especially important for pregnancy planning) 3, 1
• Anti-RNP antibodies 3

Organ-Specific Assessment

Renal Assessment

• Urinalysis with microscopy 1
• Urine protein-to-creatinine ratio 1
• Renal function tests (BUN, creatinine, GFR) 1
• Renal biopsy if significant proteinuria (>0.5g/24h), active urinary sediment, or unexplained renal insufficiency 1

Neurological Assessment (if symptoms present)

• MRI of the brain (T1/T2, fluid-attenuating inversion recovery) 3, 1
• Cerebrospinal fluid analysis to exclude infection 1
• EEG for seizure disorders 1
• Cognitive function testing for suspected cognitive dysfunction 1
• Nerve conduction studies for peripheral neuropathy 1

Cardiovascular Assessment

• Blood pressure measurement 3, 1
• Lipid profile 3, 1
• Fasting blood glucose 3, 1
• ECG (baseline) 1
• Echocardiogram if cardiac symptoms present 1

Disease Activity and Damage Assessment

• Use validated disease activity indices at each visit 3, 1:
  • SLEDAI (SLE Disease Activity Index)
  • BILAG (British Isles Lupus Assessment Group)
  • SLAM (Systemic Lupus Activity Measure)
• Annual evaluation using SLICC/ACR Damage Index 3, 1

Comorbidities Screening

Cardiovascular Risk Assessment (annually)

• Smoking status 3, 1
• Physical activity level 3
• Family history of cardiovascular disease 3, 1
• Body mass index and/or waist circumference 3, 1
• Blood pressure 3, 1
• Blood cholesterol 3, 1
• Fasting glucose 3, 1

Infection Risk Assessment

• HIV screening based on risk factors 3, 1
• Hepatitis B and C screening (especially before immunosuppressive therapy) 3, 1
• Tuberculosis screening (especially before immunosuppressive therapy) 3, 1

Bone Health Assessment

• Calcium and vitamin D intake 3, 1
• Exercise habits and smoking status 3, 1
• Bone density screening for patients on steroids or at risk for osteoporosis 3, 1

Cancer Screening

• Follow age-appropriate cancer screening guidelines for the general population 3, 1
• Special attention to cervical cancer screening 3, 1

Monitoring and Follow-up

• Disease activity assessment at each visit 3, 1
• Organ damage assessment annually 3, 1
• Quality of life assessment at each visit 3, 1
• Comorbidities assessment annually 3, 1
• Drug toxicity monitoring based on specific medications 3, 1

Special Considerations

Pregnancy Planning

• Anti-Ro/SSA and anti-La/SSB antibodies (risk for neonatal lupus) 3, 1
• Antiphospholipid antibodies (risk for pregnancy complications) 3, 1

Medication Monitoring

• Hydroxychloroquine: baseline and annual ophthalmologic examination 1
• Glucocorticoids: bone density, glucose, blood pressure monitoring 1
• Immunosuppressants: complete blood count, liver and kidney function tests 1

Common Pitfalls to Avoid

1. Relying solely on ANA testing without clinical correlation (low predictive value in primary care populations) 2
2. Failing to assess for specific organ involvement based on symptoms 1
3. Inadequate monitoring of disease activity and medication toxicity 3, 1
4. Not screening for comorbidities that affect morbidity and mortality 3, 1
5. Overlooking the need for regular assessment of cardiovascular risk factors 3, 1

Remember that SLE diagnosis requires a comprehensive approach, as no single test can definitively diagnose the condition. The 2019 EULAR/ACR classification criteria are estimated to be 96.1% sensitive and 93.4% specific for SLE 4, though these are primarily used for research purposes rather than clinical diagnosis.