How is vasculitis diagnosed?
If you think you may be developing vasculitis you must see your doctor as soon as possible. Infections, drugs and some foods can sometimes cause vasculitis, so your doctor will probably ask about the medications you've been taking and your general health during the past few weeks.
What tests are there?
There are many tests that may be done to help diagnose the condition. In this section we'll look at the most common, but there are others that you may need. Ask your rheumatologist, other specialist or GP if you're not sure about what a certain test will involve.
Blood tests may be used to measure inflammation – for example, the erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP).
A full blood count can help to establish whether you have anaemia and whether you have normal levels of white blood cells (which fight infections) and platelets (which are involved in clotting).
Blood tests for antineutrophil cytoplasmic antibodies (ANCA) are important in the diagnosis of some types of vasculitis, particularly:
- granulomatosis with polyangiitis
- eosinophilic granulomatosis with polyangiitis
- microscopic polyangiitis.
The following tests may be used to check how your kidneys are working:
- a urea and elecrolytes (U&E) test
- an estimated glomerular filtration rate test (eGFR)
- a creatinine test.
Liver function tests may also be carried out to check how your liver is working.
If you have vasculitis along with other conditions, such as rheumatoid arthritis or lupus, then blood tests might be used to assess how active these other diseases are. Blood tests can measure the level of rheumatoid factor in rheumatoid arthritis, or the levels of complement (an enzyme system or group of proteins in the blood) and antibodies in lupus.
Blood tests may be repeated from time to time to check how your condition is responding to treatment.
Other tests may be carried out to see how the affected body organs are working – for example:
- Urine tests will show the presence of blood and/or protein, which are often the first signs of an inflamed kidney. People with eosinophilic granulomatosis with polyangiitis, granulomatosis with polyangiitis or microscopic polyangiitis will have regular urine tests for blood and protein.
- X-rays, CT and MRI scans can be used to check for chest problems.
- Echocardiograms and electrocardiograms can be used to assess the heart. An echocardiogram is a special ultrasound test and an electrocardiogram (ECG) is an electrical test.
- A biopsy may be needed to confirm whether the kidneys, muscles, skin or lungs are affected by vasculitis. A small piece of tissue is removed from the organ in question for examination or testing in a laboratory.
- An ear, nose and throat (ENT) assessment may be needed for people with granulomatosis with polyangiitis who have symptoms in these parts of the body.
- An angiogram is often done where abdominal organs such as the kidney and gut are involved. This involves injecting dye into the arteries so that they show up on an x-ray. They can also be done in Takayasu arteritis and giant cell arteritis to see how much the large blood vessels are involved.