Anti-citrullinated protein antibody analysis
What is an anti-citrullinated protein assay?
The assay is based on an enzyme-linked immunosorbent assay, which detects the presence of anti-citrullinated protein antibodies (ACPAs) in the blood. These antibodies are a serologic biomarker for the autoimmune disease rheumatoid arthritis, which is a progressive autoimmune diseases that causes pain, swelling and stiffness in the joints. ACPAs are typically found in more than 75 percent of individuals suffering from rheumatoid arthritis.
Why is a ACPA assay needed?
An ACPA assay is used to help diagnose rheumatoid arthritis. It is often done along with or after a rheumatoid factor (RF) test. Many studies have shown that ACPAs provide a more accurate diagnosis of rheumatoid arthritis compared with RF testing.
You may need this test if you have symptoms of rheumatoid arthritis. These include:
- Joint pain
- Joint stiffness, especially in the morning
- Joint swelling
- Fatigue
- Low-grade fever
What happens during a ACPA assay?
A small blood sample is needed, which is to be tested in our in-house assay. If your ACPA results are positive, it means these antibodies are found in your blood, whereas a negative result means no ACPAs were detected.
If you have symptoms of rheumatoid arthritis, and your results show:
- ACPA positive and RF positive, it likely means that you have rheumatoid arthritis.
- ACPA positive and RF negative, it may indicate you are in the early stages of rheumatoid arthritis or will develop it in the future.
- negative ACPA and negative RF, it means you are less likely to have rheumatoid arthritis. Your provider may need to do more tests to help find out what is causing your symptoms.