The following tests are used to diagnose MPA:
Blood tests: Blood tests show a raised ESR and increase in number of white blood cells. The level of an antibody called ANCA especially the MPOANCA type is raised. Rheumatoid factor may be high in some patients. Patients with kidney disease may show an increase in blood urea nitrogen and creatinine levels in the blood.
Urine Examination: Urine may show protein, blood and sediments in MPA patients with kidney disease.
Chest x-ray: Chest x-ray may indicate if the lungs are affected.
CT scan, mesentric angiography, endoscopy: These tests may be useful if the digestive tract is affected.
ECG: ECG is useful if the heart is affected.
EMG: EMG is useful to diagnose nerve involvement.
Biopsy: Biopsy of the affected tissues helps in the diagnosis of MPA.