What is the diagnostic workup for Systemic Lupus Erythematosus (SLE)?

From the Guidelines

A lupus workup involves a comprehensive evaluation to diagnose systemic lupus erythematosus (SLE), prioritizing morbidity, mortality, and quality of life as the primary outcomes. Begin with a thorough history and physical examination, focusing on characteristic symptoms like joint pain, skin rashes, fatigue, and photosensitivity. Laboratory testing should include complete blood count, comprehensive metabolic panel, urinalysis, erythrocyte sedimentation rate, and C-reactive protein to assess inflammation. Specific autoantibody tests are crucial, particularly antinuclear antibody (ANA), which is positive in over 95% of lupus patients 1. If ANA is positive, proceed with more specific antibody tests including anti-double-stranded DNA, anti-Smith, anti-Ro/SSA, anti-La/SSB, and antiphospholipid antibodies. Complement levels (C3 and C4) are often decreased in active lupus. Additional testing may include chest X-ray, echocardiogram, and renal function tests to evaluate organ involvement. In some cases, tissue biopsy (skin or kidney) may be necessary to confirm diagnosis or assess disease severity. The diagnosis is ultimately based on clinical presentation and laboratory findings, using classification criteria such as the SLICC or ACR criteria, which require multiple clinical and immunological criteria to be met 1.

Key Considerations

• The 2019 update of the EULAR recommendations for the management of SLE emphasizes the importance of hydroxychloroquine in all patients with lupus, at a dose not exceeding 5 mg/kg real body weight, and minimizing glucocorticoids to less than 7.5 mg/day (prednisone equivalent) during chronic maintenance treatment 1.
• The use of immunomodulatory agents, such as methotrexate, azathioprine, and mycophenolate, can expedite the tapering or discontinuation of glucocorticoids 1.
• Belimumab may be considered in persistently active or flaring extrarenal disease, while rituximab may be considered in organ-threatening, refractory disease 1.
• Patients with SLE should be assessed for their antiphospholipid antibody status, infectious and cardiovascular diseases risk profile, and preventative strategies should be tailored accordingly 1.

Laboratory Testing

• Complete blood count
• Comprehensive metabolic panel
• Urinalysis
• Erythrocyte sedimentation rate
• C-reactive protein
• Antinuclear antibody (ANA)
• Anti-double-stranded DNA
• Anti-Smith
• Anti-Ro/SSA
• Anti-La/SSB
• Antiphospholipid antibodies
• Complement levels (C3 and C4)

Imaging and Biopsy

• Chest X-ray
• Echocardiogram
• Renal function tests
• Tissue biopsy (skin or kidney) if necessary to confirm diagnosis or assess disease severity.

From the Research

Lupus Workup

• The workup for lupus typically involves a combination of clinical evaluation, laboratory tests, and imaging studies to confirm the diagnosis and assess disease activity 2.
• Hydroxychloroquine (HCQ) is a commonly used medication in the treatment of systemic lupus erythematosus (SLE), and its blood levels can be measured to assess adherence and disease activity 3.
• The therapeutic range for HCQ blood levels is 500-2000 ng/ml, and patients with levels within this range tend to have lower disease activity 3.

Diagnosis and Management

• The diagnosis of SLE is based on a combination of clinical and laboratory criteria, including the presence of autoantibodies, immune complexes, and complement activation 2.
• The management of SLE involves a multidisciplinary approach, including lifestyle changes, prevention of comorbidities, and the use of immunomodulators and immunosuppressants 2.
• HCQ is a key component of SLE treatment, and its use has been shown to decrease disease activity, prevent flares, and reduce the need for glucocorticoids 4, 5.

Hydroxychloroquine Dosage

• The optimal dosage of HCQ in SLE patients is a matter of debate, with some studies suggesting a daily dose of ≤5 mg/kg/day actual body weight 4.
• Other studies have found that a stable dose of 200 mg/day (or 3.0-3.5 mg/kg/day) is effective in achieving prolonged remission in SLE patients 6.
• The weight-adjusted dose of HCQ does not appear to differ between patients who achieve prolonged remission and those who do not 6.

Safety and Efficacy

• HCQ is generally safe and well-tolerated, but it can cause retinal toxicity, a rare but serious complication of prolonged use 5.
• The benefits of HCQ in SLE patients include reduced disease activity, prevention of flares, and reduced organ damage, as well as antithrombotic and metabolic effects 4, 5.