Perinuclear Antineutrophil Cytoplasmic Antibodies (P-ANCA) Test

Ulcerative colitis, Churg Strauss syndrome, Wegener granulomatosis

ANCA-P test is a test that detects anti-neutrophil cytoplasmic antibodies in your blood. Antibodies are proteins that help in fighting against foreign substances. But ANCA as an anti-neutrophil antibody attacks healthy cells of the body and leads to several disorders. An ANCA test is most often used to find out if you have a type of autoimmune vasculitis.

ANCA are of two types that target a specific protein inside white blood cells:

• ANCA-P- A type of anti-neutrophil cytoplasmic antibody that targets a protein called Myeloperoxidase (MPO).
• ANCA-C- The second type of ANCA targets a protein called Proteinase (PR3).

The p-ANCA test can show whether you have one or both types of antibodies and help to diagnose several autoimmune diseases. These immune-mediated diseases cause inflammation, swelling of blood vessels, tissue damage and organ failure and need early detection for treatment.

A p-ANCA test helps detect, diagnose and monitor systemic vasculitis (an autoimmune disorder); also, it helps distinguish between the type of IBD (inflammatory bowel disease), either Crohn's disease or ulcerative colitis.

Along with detection, it's also important to interpret the results of the p-ANCA test carefully. In the case of a negative result, your symptoms are probably not the result of autoimmune vasculitis. But, if your test results are positive, you may have autoimmune disorders.

Consequently, after diagnosing the autoimmune disorders and p-ANAC testing is positive, there is a need for an additional test like a biopsy to confirm the diagnosis. The doctor will consider your signs and symptoms as well as the results of the laboratory tests and other types of tests, including imaging studies, to confirm the diagnosis of auto-immune disorders.

Additionally, the p-ANCA test is also known as the MPO test, where MPO stands for Myeloperoxidase. The p-ANCA test is done if one has a fever, muscle aches and weight loss, impaired kidney or lung function, chronic diarrhoea or abdominal pain.

In several studies, 90% of patients are diagnosed positive with microscopic polyangiitis (MPA) in the p-ANCA test. The p-ANCA test detects a positive result in 40% of the cases of Churg Strauss or Granulomatosis with Polyangiitis.

Other names of the p-ANCA Test

• ACPA test

• ACNA test

• Cytoplasmic antibody test

• Myeloperoxidase antibodies test
• Serum anti-cytoplasmic antibodies test
• Wegener's Disease test

What does the p-ANCA test measure and who is this prescribed for?

The p-ANCA test measures the levels of perinuclear antineutrophil antibodies in the blood. High positivity can affect several health conditions related to the body or damage the body.

Improper functioning of the immune system and the presence of anti-neutrophil antibodies is indicated if a person is experiencing the following conditions:

• Redness, itching, and stiffness in the eyes
• Problems with vision like loss of vision, blurred vision
• Skin rashes or sores
• Running nose
• Shortness or difficulty breathing
• Respiratory problems
• Hearing loss or problems with hearing
• Kidney problems like proteinuria (the presence of protein in the urine)
• Diarrhoea (continues watery passing of stool)
• Mild to severe abdominal pain
• Abdominal cramps
• Fever
• Fatigue

For people with such complaints, amongst other tests, the p-ANCA test is prescribed by the consulting physician.

Some disease conditions for which a p-ANCA test can be prescribed are:

• Rectal bleeding
• Low growth and development in children
• Wegener's granulomatosis
• Kidney diseases
• Microscopic polyangiitis

Following a diagnosis, an immunologist, rheumatologist or physician will initiate treatment for auto-immune disorders. The p-ANCA test may be prescribed every 6 months to monitor and regulate the dosage.

By analyzing the results of the p-ANCA test, your doctor can determine whether to continue the same treatment or modify its dosage. The p-ANCA test applies to males and females, both adults and children.

The abnormal presentation of perinuclear antineutrophil cytoplasmic antibodies can affect the patient's health. The detection of p-ANCA in the blood can be affected by several factors related to the patient.

The normal ranges for detection are:

• The presence of anti-neutrophil antibodies is considered negative when it has a range lower than or equal to 19AU/mL.

• The presence is determined as equivocal when it has a range of 20 - 25 AU/mL.

• The presence is determined as positive when it has a range greater than or equal to 26 AU/mL.

Although, these normal ranges may vary between several laboratories as different laboratories have different methods of testing.

Anti-neutrophil cytoplasmic antibodies present in the blood may cause several auto-immune disorders, including auto-immune vasculitis, inflammatory bowel disorders, etc. The component of the p-ANCA test is to detect the anti-neutrophil antibodies which are attacking the healthy cells of the body.

When the p-ANCA value is higher than normal, our body antibodies attack our cells. A higher p-ANCA reading would point to the improper functioning of the immune system. This interpretation of the p-ANCA test indicates the immune system is not functioning properly, causing the body to attack its own tissues, which results in various auto-immune diseases.

High presence of p-ANCA results in these conditions:

• Autoimmune vasculitis: This condition is characterized by inflammation of the blood vessels and changes in their walls. It is caused by the presence of perinuclear antineutrophil cytoplasmic antibodies. This inflammation can cause vessel walls to thicken, narrow and disrupt the vital blood supply to the tissues and organs of the body.

• Churg-Strauss Syndrome: A disease that is frequently associated with asthma and allergies. It is caused by the swelling of certain types of blood or tissue cells. It is also known as eosinophilic granulomatosis with polyangiitis.

• Microscopic polyangiitis: A rare condition associated with an inflammation of blood vessels that damages nerves, skin, joints, kidneys, etc. It is an autoimmune disease caused commonly by high levels of p-ANCA in the blood.

• Wegener's disease: A type of vasculitis (inflammation in blood vessels) in which ears, nose, throat, lungs and kidneys are majorly damaged. It is a rare disease caused by the high presence of p-ANCA or an uncertain cause that affects people of all ages. It is also called granulomatosis with polyangiitis.

• Ulcerative colitis (UC): An inflammatory bowel disease that causes inflammation in the digestive tract. Usually, it only occurs in the inner lining of the large intestine (colon) and rectum.

Negative Presence of p-ANCA test

The negative presence of the p-ANCA test means you don't have autoimmune vasculitis or any other health condition related to p-ANCA.

A simple blood sample is needed to undergo a perinuclear antineutrophil cytoplasmic antibody test. No specific preparation needs.

Test preparation:

A p-ANCA test is a serum blood test that does not require any preparation. The usual way to collect a blood sample is by drawing it from one of the forearm veins. The collected sample is sent to a laboratory for analysis. This procedure is simple, lasts for 5 minutes and does not have any risk.

What are the parameters included in the test?

The peripheral antineutrophil cytoplasmic antibody test measures the presence of antineutrophil antibodies in the blood.

These values give an idea about the presence of anti-neutrophil antibodies that leads to several auto-immune disorders. The result of the p-ANCA test is not expressed as positive or negative.

If the value is on the higher side or lower side, it is an indicator of a disorder with the immune system. This p-ANCA test evaluates the changes at the organ level or changes in the body in the body's immune system.

How frequently should you take this test?

A test after every 3 months may be recommended if you have perinuclear antineutrophil cytoplasmic antibodies in the blood. Testing for p-ANCA in the blood serves as a monitoring tool for the treatment of several health conditions.

If the previous test results are normal or the presence of p-ANCA is not detected in the blood, you may repeat the test on an annual basis.