Investigations for systemic vasculitides

Blood investigations that may support the diagnosis of systemic vasculitides include:

  • full blood examination—anaemia, leukocytosis, thrombocytosis
  • inflammatory markers—raised serum C-reactive protein (CRP) concentration and erythrocyte sedimentation rate (ESR)
  • organ-specific investigations, including
    • kidney function tests (eg serum electrolyte and creatinine concentrations, glomerular filtration rate (GFR), urinalysis)
    • liver biochemistry
  • antineutrophil cytoplasmic antibody (ANCA).

Specific testing for ANCAs may be helpful in diagnosing ANCA-associated vasculitides1 but should only be requested if the clinical presentation is highly suggestive of one of these conditions. For example, consider ANCA testing in people with a vasculitic rash, acute glomerulonephritis, pulmonary haemorrhage, or refractory ear, nose and throat symptoms.

Note: Only request an antineutrophil cytoplasmic antibody (ANCA) titre if a specific ANCA-associated vasculitis is suspected.

Tissue biopsy can confirm a diagnosis for most of the systemic vasculitides; the hallmark finding is vascular inflammation in affected tissue(s). The choice of tissue or organ for biopsy is directed by the clinical presentation.

Imaging may be useful to identify vasculitis affecting larger blood vessels that cannot be easily accessed for biopsy, such as the aorta or splanchnic vasculature. Imaging modalities that can confirm the diagnosis, without the need for biopsy, include:

  • magnetic resonance imaging (MRI) scan
  • computed tomography angiography (CTA)
  • positron emission tomography (PET) scan.
1 Antineutrophil cytoplasmic antibody (ANCA)–associated vasculitides include eosinophilic granulomatosis with polyangiitis (EGPA), granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA).Return