How is Wegener granulomatosis diagnosed?
The diagnosis is not always straightforward. Blood count abnormalities may include: • Raised white cell count (leucocytosis) • Reduced haemoglobin (normocytic normochromic anaemia) • Raised platelet count (thrombocytosis) • Raised erythrocyte sedimentation rate (ESR) Antineutrophil cytoplasmic antibody (ANCA) is the most useful blood test. A particular type of ANCA is highly specific for Wegener granulomatosis. It is recognised by cytoplasmic staining pattern and is directed against an enzyme, proteinase-3. A positive test result for rheumatoid factor occurs in 50-60% of patients and can be misleading because this normally indicates rheumatoid arthritis. A skin biopsy may be helpful if it demonstrates granulomatous vasculitis (inflamed blood vessels with a certain pattern of inflammation).
