From the Guidelines
A vasculitis workup should begin with a thorough history and physical examination, followed by laboratory tests including complete blood count, comprehensive metabolic panel, erythrocyte sedimentation rate, C-reactive protein, urinalysis, and antineutrophil cytoplasmic antibodies (ANCA) as recommended by the most recent guidelines 1. The initial evaluation should also include tests such as rheumatoid factor, antinuclear antibodies, complement levels (C3, C4), cryoglobulins, hepatitis B and C serologies, and HIV testing to help identify potential underlying causes or associated conditions. Imaging studies are essential in the diagnostic process, with options including:
- Chest X-ray
- CT scans of affected areas
- MRI
- Angiography to visualize vessel inflammation These imaging modalities can help detect organ involvement and identify potential biopsy sites, as noted in the 2022 update of the EULAR recommendations for the management of ANCA-associated vasculitis 1. A biopsy of the affected tissue provides definitive diagnosis and should be performed when possible, as it is strongly supportive of a diagnosis of vasculitis and can help distinguish active disease from damage as the cause of clinical decline 1. Specialized tests may be needed based on suspected vasculitis type, such as:
- Temporal artery biopsy for giant cell arteritis
- Pulmonary function tests for granulomatosis with polyangiitis This comprehensive approach is necessary because vasculitis presents with varied symptoms depending on which blood vessels are affected, and proper diagnosis guides appropriate treatment, which often includes corticosteroids and immunosuppressants like cyclophosphamide, methotrexate, or rituximab depending on the specific type and severity of vasculitis. The use of ANCA testing, including indirect immunofluorescence and ELISA, is recommended in the appropriate clinical context, as stated in the EULAR recommendations for the management of primary small and medium vessel vasculitis 1. In patients with pulmonary lesions that cannot be clearly attributed to active AAV, thoracoscopic or open lung biopsies can be considered, as suggested in the 2022 update of the EULAR recommendations for the management of ANCA-associated vasculitis 1. Surrogate markers, such as clinical parameters (e.g., mononeuritis multiplex confirmed by electrophysiological studies), laboratory data (e.g., red blood cell casts in the urine suggestive of glomerulonephritis), or findings on imaging, can support a clinical diagnosis of AAV when a biopsy is not feasible or when the results are inconclusive 1.
From the Research
Vasculitis Workup
- The diagnosis of vasculitis can be challenging due to its diverse clinical presentation and organ manifestations 2.
- A careful patient history, thorough physical examination, and selected laboratory tests are essential for a tentative diagnosis of vasculitis 3, 4.
- Recognizing the pattern of organ involvement provides a clue to the type of vasculitis present 3.
- Serologic laboratory tests, such as ANCAs, hepatitis B or C, and other autoantibodies, can help confirm the presence of underlying vasculitis 3, 5.
- A definitive diagnosis can be confirmed by a biopsy of involved tissue or by angiography 3, 4.
Laboratory Tests
- Routine laboratory tests include erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), blood count, serum creatinine, urinalysis, specific autoantibodies, complement, immunoglobulin, cryoglobulin, and Hepatitis B and C serology 5.
- Autoantibodies, such as anti-neutrophil cytoplasmic antibodies (ANCAs), anti-glomerular basement membrane (GBM) antibodies, and anti-C1q antibodies, are helpful for diagnosis 5.
- High-quality antigen-specific immunoassays are the preferred screening methodology for the diagnosis of ANCA-associated vasculitis 5.
Diagnosis and Treatment
- The diagnosis of systemic vasculitis is challenging, and laboratory testing may provide useful information 5.
- Accurate categorization of vasculitic disorders is essential, as prompt and aggressive therapy with potentially toxic drugs is necessary to avoid irreversible organ system dysfunction 4.
- Different treatments for patients with granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) have been compared in a systematic review and meta-analysis to inform evidence-based recommendations for the American College of Rheumatology (ACR)/Vasculitis Foundation (VF) Vasculitis Management Guidelines 6.