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Diseases > Granulomatosis with Polyangiitis (GPA) > What is it?

What is Granulomatosis with Polyangiitis?

Granulomatosis with polyangiitis is also known as Wegener’s Granulomatosis. It is an inflammatory disorder that mainly affects very small blood vessels in the respiratory tract. Both the upper airway (sinuses, nasal cavity, windpipe) and lower airway (lungs) can be involved. The disorder may also affect small blood vessels supplying the kidneys and other tissues throughout the body.

What causes Granulomatosis with Polyangiitis?

At this time, the exact cause of Granulomatosis with polyangiitis is not fully understood. It is thought to be an autoimmune disease. This means that something causes your immune system to go awry. The initial trigger is not known, but some experts speculate that an infection could set it off. However, no specific infection has yet been identified as a cause. Whatever the trigger, the immune system begins to attack the small blood vessels throughout the body and causes inflammation.

The word inflammation comes from the Latin word inflammare which means to light on fire. You can think of it like this: in people with Granulomatosis with polyangiitis, small blood vessels in certain areas of the body are “on fire” and are eventually damaged. This can cut off blood supply to vital areas of the body.

Who gets Granulomatosis with Polyangiitis?

Granulomatosis with polyangiitis is a rare disorder. It is estimated to affect only 1 person in every 25,000. So, if you live in a city with 250,000 people then you could expect about 10 people to have Granulomatosis with polyangiitis. So you can see that this disorder is really quite rare.

Granulomatosis with polyangiitis affects men and women equally. The disorder usually strikes people in middle age, but younger and older people can also develop the condition.

How is Granulomatosis with Polyangiitis diagnosed?

Granulomatosis with polyangiitis can come on very gradually and it can take time before it’s accurately diagnosed. In some people, it may take several years before a correct diagnosis is made. In other people, the disorder is more obvious from the start.

Granulomatosis with polyangiitis is usually diagnosed by a specialist physician, depending on what areas of the body are affected. If the airways are the problem, it might be diagnosed by a respirologist. If the kidneys are involved, it might be a nephrologist (a kidney specialist). Often times, Granulomatosis with polyangiitis is diagnosed by a rheumatologist.  A rheumatologist is a specialist in arthritis and autoimmune diseases.

Your physician will take a complete history and perform a thorough physical examination. This is usually followed by blood tests, x-rays and other types of tests.

What tests are done to diagnose Granulomatosis with Polyangiitis?

When Granulomatosis with polyangiitis is suspected, special blood tests can help to confirm the diagnosis. However, in some people these blood tests can be normal and yet the person might still have Granulomatosis with polyangiitis. A blood test alone is usually not enough to diagnose Granulomatosis with polyangiitis. The best way to confirm the diagnosis is with a tissue biopsy. This involves taking a very small sample of tissue through a needle. This is most effective when the kidneys and/or lungs are involved. A biopsy from the sinuses is not always helpful.

Other tests that can help make a diagnosis of Granulomatosis with polyangiitis include:

  • Complete blood count (CBC)
  • Anti-neutrophil cytoplasmic autoantibodies (ANCA) test
  • Hemoglobin and ferritin (to test for anemia or low blood iron)
  • Erythrocyte sedimentation rate (ESR)
  • C-reactive protein (CRP)
  • Kidney function tests
  • Urinalysis to look for protein or blood in the urine – a sign the kidneys are involved
  • Chest x-ray and/or CT scan to look for lung involvement
  • CT scan or MRI of the head and neck to look for involvement of the upper respiratory tract

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