I order these labs quite often in my patients whom I suspect may have rheumatoid arthritis. Rheumatoid arthritis (RA) is a chronic autoimmune disease that primarily affects the joints. It can lead to pain, swelling, and even joint damage over time. To help diagnose and manage this condition, doctors often order specific blood tests.
In this blog post, I will go over four important lab tests: CCP antibodies, 14-3-3 ETA protein, Anti-CarP, and Rheumatoid Factor. By the end of this article, you’ll have a clearer understanding of what these tests are, why they matter, and how they contribute to diagnosing and managing rheumatoid arthritis.
What is Rheumatoid Arthritis?
Before diving into the lab tests, let’s briefly discuss what rheumatoid arthritis is. RA is an autoimmune disorder, meaning that the body’s immune system mistakenly attacks its own healthy tissues. This can lead to inflammation in the joints and other organs as well.
Over time, if left untreated, RA can cause joint damage and loss of function. Every patient gets affected by RA differently. I have seen some patients have no pain but have changes to their hands. I have had other patients with only lung manifestations of their RA where their RA attacked their lungs as their first manifestation with symptoms of shortness of breath.
What are CCP Antibodies?
CCP stands for cyclic citrullinated peptide. When the body produces antibodies against these peptides, it indicates that the immune system is attacking its own tissues. The presence of CCP antibodies is a strong indicator of rheumatoid arthritis. CCP antibodies are very specific for rheumatoid arthritis. When I see CCP antibodies, it means the patient either has RA or is at risk of having RA. Higher levels of CCP antibodies makes it more likely the patient has rheumatoid arthritis. Having CCP antibodies can carry a worse prognosis compared to someone that does not have CCP antibodies.
What is 14-3-3 ETA Protein?
The 14-3-3 ETA protein is another marker found in the blood that can indicate inflammation and autoimmune activity. It can be a sign of early rheumatoid arthritis when it is positive. Not many labs have this test available. This test can be obtained at Quest Diagnostics in the USA.
What is Anti-CarP?
Anti-CarP stands for anti-citrullinated protein antibodies. Similar to CCP antibodies, these proteins indicate that the immune system is attacking its own proteins. The Anti-CarP test is specific for rheumatoid arthritis as well. However, it is not as popular as the CCP antibodies. This is a newer test compared to the CCP antibody. When I see Anti CarP antibodies positive on the test results, it makes it more likely that the patient has rheumatoid arthritis compared to another arthritis.
What is the Rheumatoid Factor?
The Rheumatoid factor is an antibody that can be found in the blood of people with RA and other autoimmune diseases. They are proteins produced by the immune system when it mistakenly targets its own tissues.
The rheumatoid factor is not specific for rheumatoid arthritis only. It can be found in other diseases such as hepatitis C, cryoglobulinemia, MCTD, tuberculosis, and endocarditis. Its called rheumatoid factor because it was first discovered in patients with rheumatoid arthritis back in the 1940s. However, since then they have found it in other diseases as well so thats why the name has stuck with rheumatoid factor.
When I see rheumatoid factor positive, it makes me think of RA but I am also looking for other diagnoses as well.
Understanding these four key rheumatoid labs—CCP antibodies, 14-3-3 ETA protein, Anti-CarP, and Rheumatoid Factor can help you understand Rheumatoid Arthritis better. It will also help you be better informed when your doctor runs these labs as you will have a more educated discussion with them next time you are in their office.
THANK YOU! This is absolutely wonderful information, written very well to understand and something to work with.