What serum labs are recommended for diagnosing and treating cerebral vasculitis?

Recommended Serum Laboratory Tests for Cerebral Vasculitis

For diagnosing and monitoring cerebral vasculitis, a comprehensive panel of serum laboratory tests including complete blood count with differential, ANCA testing, inflammatory markers, renal function tests, and targeted serologies based on clinical presentation is essential. 1

Initial Diagnostic Workup

Core Laboratory Tests

• Complete blood count with differential

  • Identifies anemia, leukocytosis, and eosinophilia (>1500 cells/μl or >10% suggestive of EGPA) 1
  • Platelet count to assess for thrombocytosis or thrombocytopenia

• ANCA testing

  • Indirect immunofluorescence for c-ANCA and p-ANCA patterns
  • ELISA for specific antibodies (PR3-ANCA and MPO-ANCA)
  • PR3-ANCA (c-ANCA) highly specific for GPA
  • MPO-ANCA (p-ANCA) associated with MPA and EGPA 1, 2

• Inflammatory markers

  • Erythrocyte sedimentation rate (ESR)
  • C-reactive protein (CRP) 1

• Renal function assessment

  • Serum creatinine
  • Blood urea nitrogen (BUN)
  • Estimated glomerular filtration rate (eGFR) 1
  • Urinalysis with microscopic examination 2

Additional Targeted Tests

• Immunoglobulin levels (IgG, IgA, IgM)

  • Important to check before potential IVIG therapy 2
  • Hypoimmunoglobulinemia may occur after rituximab treatment 2

• Cryoglobulins (for suspected cryoglobulinemic vasculitis) 1

• Hepatitis B and C serology

  • Essential for identifying infection-associated vasculitis 1, 3

• HIV testing

  • Important for identifying potential co-infection with other causes like neurosyphilis 4

• Syphilis serology (VDRL, RPR, TPPA)

  • When infectious causes are suspected 3, 4

• Anti-phospholipase-A2-receptor antibodies

  • For cases with suspected renal involvement 1

Disease-Specific Testing

For ANCA-Associated Vasculitis

• PR3-ANCA and MPO-ANCA by ELISA
• Anti-glomerular basement membrane antibodies (to rule out Goodpasture syndrome) 2

For Suspected Systemic Involvement

• Rheumatoid factor
• Antinuclear antibodies (ANA)
• Complement levels (C3, C4, CH50)
• Anti-double stranded DNA 1

Monitoring Disease Activity

• Serial ANCA testing

  • Useful for monitoring disease activity and predicting relapse 1
  • Note: Clinical assessment should guide treatment decisions rather than ANCA testing alone 2

• Regular monitoring of inflammatory markers

  • ESR and CRP to assess response to therapy 1

• Renal function tests

  • Regular monitoring for kidney involvement 1

Important Caveats

• Laboratory findings must be interpreted in the context of clinical presentation and imaging results 5
• Negative serology does not exclude cerebral vasculitis, particularly in primary angiitis of the central nervous system (PACNS) 6
• Anti-neutrophil cytoplasmic antibody assay may be abnormal in only a subset of patients with cerebral vasculitis (positive in 3/8 patients in one study) 7
• Consider ophthalmological examination using low-dose fluorescein angiography with slit-lamp video microscopy, which may reveal abnormalities in some patients 7

Follow-up Laboratory Testing

• Frequency of monitoring should be based on disease severity and treatment regimen
• More frequent monitoring during active disease and after changes in therapy
• Regular assessment of medication-related toxicities (e.g., CBC, liver function tests, and renal function for patients on immunosuppressants) 1

Remember that cerebral vasculitis is a rare condition, and laboratory tests should be interpreted alongside clinical presentation, CSF studies, and neuroimaging findings to establish the diagnosis and guide treatment decisions.