From the Guidelines
Systemic vasculitis diagnosis involves a combination of clinical assessment, laboratory tests, and imaging studies. The diagnostic tests for systemic vasculitis include:
- ANCA testing: anti-neutrophil cytoplasmic antibody (ANCA) testing, including indirect immunofluorescence and ELISA, should be performed in the appropriate clinical context 1
- Biopsy: a positive biopsy is strongly supportive of vasculitis and is recommended to assist diagnosis and further evaluation for patients suspected of having vasculitis 1
- Urine analysis: microscopic hematuria with dysmorphic red blood cells and red cell casts, and proteinuria that is usually moderate (1–3 g/d) are common findings in patients with systemic vasculitis 1
- Imaging studies: imaging studies such as angiography, MRI/CT imaging, and neurophysiology may be used to support the diagnosis of systemic vasculitis 1
- Clinical assessment: a structured clinical assessment, including a checklist of common items affecting various systems in vasculitis, should be conducted at each clinic visit to detect new organ involvement 1
- Laboratory tests: laboratory tests such as CRP and/or ESR should be determined regularly as serologic markers of disease activity, and renal function should be assessed by the GFR using estimating equations such as the MDRD or Cockroft–Gault formula 1
The diagnosis of systemic vasculitis should be based on a combination of these tests and a thorough clinical evaluation. The clinical manifestations associated with systemic vasculitis include microscopic hematuria, proteinuria, and rapidly declining glomerular filtration rate (GFR) over days or weeks 1. A positive test for anti-glomerular basement membrane (GBM) antibodies suggests anti-GBM disease, while a positive test for myeloperoxidase (MPO)- or proteinase 3 (PR3)-ANCA supports a diagnosis of ANCA-associated vasculitis 1.
From the Research
Diagnostic Tests for Systemic Vasculitis
The diagnosis of systemic vasculitis involves various laboratory tests and imaging modalities. Some of the key diagnostic tests include:
- Antineutrophil cytoplasmic autoantibodies (ANCAs) testing, which is considered an important diagnostic tool in the work-up of patients suspected of vasculitis 2, 3, 4
- Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) to assess inflammation 3
- Blood count, serum creatinine, urinalysis, and specific autoantibodies to evaluate organ involvement 3
- Complement, immunoglobulin, and cryoglobulin tests to assess immune system dysfunction 3
- Hepatitis B and C serology to rule out infectious causes 3
- Imaging modalities such as computed tomographic angiography, magnetic resonance angiography, color Doppler ultrasound, and positron emission tomography/computed tomography to visualize vessel involvement 5, 6
Laboratory Tests
Laboratory tests play a crucial role in the diagnosis of systemic vasculitis. Some of the key laboratory tests include:
- ANCA testing, which can be performed using indirect immunofluorescence (IIF) test and antigen-specific assays 2
- Anti-glomerular basement membrane (GBM) antibodies and anti-C1q antibodies to diagnose specific types of vasculitis 3
- Autoantibody testing to evaluate immune system dysfunction 3
Imaging Modalities
Imaging modalities are essential in the diagnosis of systemic vasculitis, particularly in visualizing vessel involvement. Some of the key imaging modalities include: