Systemic Lupus Erythematosus – SLE

Systemic lupus erythematosus (SLE) is a systemic autoimmune disorder, characterized by a wide spectrum of clinical manifestations that can affect many organs, including the skin, joints, the central nervous system and the kidneys. Rare, inherited, single-gene complement deficiencies are strongly related to SLE, but the disease is inherited during a polygenic manner in most patients. because of the heterogeneity of SLE, Diagnosis remains challenging through a combination of clinical and laboratory criteria.

Panel test

• Immunologic tests:
• Complement 3, 4, and CH50 – Low levels of complement in the blood are often linked with lupus.
• Antinuclear antibody (ANA) test – it’s an initial screen (not disease-specific); In patients with a positive ANA, more tests are performed for other antibodies that can confirm the diagnosis.
• Double-stranded DNA (dsDNA) – Presence of high antibody titers to native dsDNA is specific and diagnostic for SLE
• Extractable nuclear antigens:
  • Smith (Sm) antibodies – highly specific for SLE but occur in only 30-35% of cases
  • Ribonucleic protein (RNP) antibodies – not specific for SLE
  • Anti-Sjögren’s syndrome antigen A (SSA, or Ro) and anti-Sjögren syndrome antigen B (SSB, or La) antibodies – not specific for SLE
• Histone antibodies – This test is useful for when drug-induced lupus is suspected
• Anti-ribosomal P (anti-P) – related to neurolupus but not useful in diagnosis of neuropsychiatric lupus
• Chromatin antibodies – Primary use – diagnose drug-induced lupus, 50-90% of SLE patients have these antibodies, Related to proteinuria, glomerulonephritis, and disease activity, It’s not specific for SLE, Could be found in Sjögren syndromeand antiphospholipid syndrome (APS)
• Biomarkers of lupus nephritis/disease severity:
  • Anti-C1q antibodies – existence of these antibodies can predict risk for severe of disease and it’s related to renal disease.
• Consider the following testing to rule out other diseases:
  • Antiphospholipidantibodies icluding lupus anticoagulant, anticardiolipin, and anti-beta-2 glycoprotein 1 IgG and IgM assays
  • Cryoglobulin
    • Neurolupus: CSF is tested for cell count, glucose, oligoclonal bands, culture and Oligoclonal bands, Interleukin 6, 8, 10.
  • Collagen type VII antibody IgG – could be positive in bullous SLE
• Routine tests:
• Complete blood count. anemia commonly occurs in lupus. A low white blood cell or platelet count may occur in lupus as well.
• Erythrocyte sedimentation rate (ESR) and C-Reactive Protein (CRP). ESR is usually elevated in active SLE, whereas CRP may not be.
• liver transaminases.