Microscopic Polyangiitis


The first signs of microscopic polyangiitis (MPA) are similar to the flu. People start feeling unwell and commonly have a fever, achiness, malaise and weight loss. These symptoms can last for some time. As these symptoms are common to many diseases, it can be difficult to diagnose MPA in its early stages.

Other symptoms of MPA depend on which organs are affected.


If the kidneys are involved, a patient may experience fatigue, swelling of the legs, or shortness of breath. Kidney involvement can come on slowly or in some cases very quickly leading to rapid kidney failure.


If the lungs are involved then a patient may notice shortness of breath, a cough, or chest pain/discomfort. Lung disease is due to inflammation of the lung tissue.

In some cases, lung involvement can be very dramatic and life threatening. If lung disease is very severe there can be bleeding into the lung. In this case a patient may cough up blood.

Lung involvement is usually seen on a chest x-ray or CT-scan of the chest. It can sometimes be confused with pneumonia.


Signs of MPA can also appear on the skin, usually as little red dots called purpura that can look like little bruises. These are usually found on the lower part of the body.


When MPA affects the eyes, symptoms can include conjunctivitis (redness of the eye) or inflammation of other parts of the eye (uveitis).


When MPA affects the nerves it can cause a sudden loss of strength (e.g., “foot drop” or “wrist drop”) but does not usually cause pain. Early diagnosis and treatment is important to avoid nerve damage.


When MPA affect the joints, people can experience different symptoms. Some people have obvious swelling of the joints, which can jump around from joint to joint. In others, they ache all over.


Microscopic polyangiitis (MPA) can be difficult to diagnose because there are no symptoms that are unique to the disease. In some cases, symptoms can appear quickly. Other times, they can take a while to develop (months to years).

MPA is usually best diagnosed by a rheumatologist (a specialist in arthritis and autoimmune disease).

To diagnose the disease, a physician will take a complete history and perform a thorough physical examination. They will usually order blood tests, x-rays and other types of tests to confirm their diagnosis and determine which organs might be affected by the disease.

In some cases a tissue biopsy is required to confirm the diagnosis. This involves taking a very small sample of tissue through a needle so it can be examined in a lab.

Common Tests to Diagnose MPA


Scientists don’t know what causes microscopic polyangiitis (MPA), but it is thought to be an autoimmune disease. This means that it is thought that the disease is caused by the body’s immune system attacking its own blood vessels causing inflammation.

Other similar diseases in this family include granulomatosis with polyangiitis or GPA (also known as Wegener’s granulomatosis) and eosinophilic granulomatosis with polyangiitis or EGPA (also known as Churg-Strauss). Every disease in this family are forms of vasculitis, which means they feature inflammation of blood vessels. of family feature inflammation of blood vessels (called vasculitis).


Microscopic polyangiitis (MPA) should be treated as early and aggressively as possible to prevent severe damage to the blood vessels, respiratory tract (including the lungs), kidneys, and other important tissues and organs.

Medications for microscopic polyangiitis fall into two broad groups. The first includes medications that are used initially to bring the disease under control quickly. These are called induction therapies. The second group of medications control the disease over the long-term and are called maintenance therapies.

Medications for Induction Therapy

Corticosteroids (prednisone), cyclophosphamide and rituximab help to rapidly reduce inflammation and control the symptoms associated with MPA.

Once the disease is in remission (when there are no more symptoms and markers of inflammation are back to normal), induction therapies are often tapered (reduced or even stopped in some cases).

Medications for Maintenance Therapy

Azathioprine, mycophenolate mofetil or mycophenolic acid, and methotrexate are medications that are typically used for maintenance (long-term) therapy of MPA. These medications usually take longer to begin to work. Rituximab is also being used as a chronic maintenance therapy with good success.

Maintenance medications might be overlapped with the induction therapy, but unlike induction therapies, they are usually continued over the long-term to keep the disease under control.

Corticosteroids (prednisone)

Medications like prednisone help control inflammation. They may also prevent long-term damage in some people. Prednisone is a very effective medication to control the inflammation of granulomatosis with polyangiitis. In the short-term, prednisone may be given by intravenous infusion in the hospital. After a few days, this is usually switched to oral prednisone. As symptoms improve and markers of inflammation return to normal, the dose of prednisone can be gradually reduced (tapered).

When used for long periods of time, prednisone can have side effects. You should to discuss the risks and benefits of using prednisone with your doctor. Some patients who have joint involvement also benefit from cortisone injections directly into a joint. This should be discussed with your rheumatologist.


A medication called cyclophosphamide is often used with prednisone to get the disease under control. Cyclophosphamide can be given by mouth or by intravenous infusion. If there is very serious lung, kidney or nerve involvement, an intravenous infusion may be easier to administer.

Cyclophosphamide can increase your risk of infection (be careful with fevers). Cyclophosphamide can also affect your ability to have children (fertility) – this needs to be discussed with your doctor.


This is a type of therapy called a “biologic” medicine. Rituximab has been shown to be as effective as cyclophosphamide and is now approved for the treatment of microscopic polyangiitis . Although it is more expensive, it may be appealing to women of childbearing age because it does not affect fertility. Rituximab is becoming increasingly popular as a longer term choice for maintenance therapy.


The Disease Modifying Anti-Rheumatic Drugs (DMARDs) are medications that are typically used to treat rheumatoid arthritis. Examples that have been shown to be effective in people with microscopic polyangiitis include azathioprine (Imuran), methotrexate, and mycophenolate mofetil or mycophenolic acid. In many cases the DMARDs are used for maintenance therapy once the disease is under control. In milder cases of microscopic polyangiitis they may be used initially to induce remission.

Most DMARDs take about 6-12 weeks before they begin to work. Some people might not feel any effect when they first start taking DMARDs. Even if this happens, it’s important to keep taking DMARDs to help keep inflammation under control and to maintain remission.

Living with MPA

The pain and stiffness caused by MPA can sometimes limit people’s normal activities, including work. There are many things people can do to lessen the impact of MPA on their work and daily routine.

We recommend adjusting features of the workplace to help make working with MPA easier. For example, people that sit for much of the day can adjust the position of chairs and desks for proper posture. Vehicle seats can be adjusted to make driving more comfortable and reduce stress on joints and affected tissues.

Those who find out they have MPA while they’re still young can consider choosing work that isn’t physically demanding on their joints and back.

Exercise is important to overall health. It also helps keep the joints moving properly, and helps protect them by strengthening the muscles around them.

The level and amount of exercise people with MPA can do depends on the activity of their disease.

A trained arthritis physiotherapist is the best person to help design an exercise program tailored to the needs of patients with MPA.

The following are some useful articles on exercising with arthritis:

Exercise and Arthritis: An article by arthritis physiotherapist Marlene Thompson

Exercising in a Flare: Another excellent article by Marlene Thompson on how to cope with flares through your exercise routine.

Alcoholic beverages are not an effective treatment for MPA, and they can interact with many medications.

Smoking is not healthy for people with MPA. It can make symptoms worse and harder to treat.

Research has shown that some arthritis medications do not work as well in people who smoke.

We recommend that smokers quit immediately to reduce the impact of their symptoms, improve the effectiveness of their medications, and improve their overall health.

Travel is still possible when you have MPA.

It is best for people with this disease to get organized well in advance of a trip to ensure a smooth, comfortable, and enjoyable time.

Check out our Travel Checklist page.

Though MPA does not particularly cause a loss of sex drive, it can cause pain, fatigue and emotional hardships. These hardships risk creating barriers to sexual needs, ability, and satisfaction.

People with MPA can take comfort knowing that sex and intimacy can be maintained. In many cases, it can help draw partners closer together, especially through improved communication.

For more information on intimacy and arthritis, a great book is: Rheumatoid Arthritis: Plan to Win by Cheryl Koehn, Taysha Palmer and John Esdaile.

Microscopic Polyangiitis (MPA) has no effect on fertility. The chances of getting pregnant for people with MPA are the same as with people that don’t have it. MPA also has no known effects on the developing fetus or the newborn.

The two main issues doctors worry about with MPA and pregnancy are:

Following the basics of healthy eating can help improve health and well-being in everyone, including those with MPA. Keeping a healthy weight helps reduce the load on weight-bearing joints including the spine, hips, and knees, making it easier to live with the disease.

Unfortuantely, no special diet has ever been proven to significantly alter the course of MPA or any other types of arthritis.

In addition, no known natural remedies or complementary therapies have been proven to help MPA in any significant way.

People with MPA should consult with their doctor to make sure that any supplements or alternative therapies they consume will not negatively interact with their medications.

Its very important for people with MPA to attend regularly scheduled appointments with their rheumatologist, and promptly get any tests that are ordered by their doctors.

It is often very important that medications are taken exactly as prescribed. Patients should always talk to their doctor about any issues they experience, or if they would like to change anything.

Microscopic Polyangiitis is a chronic disease and a rheumatologist is the best partner in helping patients achieve the best quality of life possible.

Additional Resources for People with MPA