Rheumatoid factor and anti-CCP antibodies
What these two antibody tests do and do not tell you, why a positive result is not a diagnosis on its own, and how a specialist assessment settles what it means for you
Rheumatoid factor (RF) and anti-CCP are blood tests often requested when rheumatoid arthritis is being considered. They can be genuinely helpful, but they are frequently misread. A positive result does not, on its own, confirm rheumatoid arthritis, and a negative result does not rule it out. This guide explains what each test looks for, what a result does and does not mean, and how a specialist assessment brings the answer into focus.
Written for patients and reviewed by Dr Liubov Borukhson, Consultant Rheumatologist (GMC 7021928). Last clinically reviewed: June 2026.
What these two tests are
Rheumatoid factor is an antibody that can be detected in the blood of many people with rheumatoid arthritis. It is the older of the two tests and has been used for decades. Anti-CCP, which stands for anti-cyclic citrullinated peptide, is a more recently available antibody test that tends to be more closely tied to rheumatoid arthritis specifically.
Both are usually requested together when symptoms such as pain, swelling and morning stiffness in several joints raise the question of an inflammatory arthritis. They are often accompanied by tests of inflammation, such as CRP and ESR, and the results are always read together rather than one at a time.
A positive rheumatoid factor is common, and not a diagnosis
This is the most important point to understand about rheumatoid factor. A positive result is not specific to rheumatoid arthritis. It is found in a number of healthy people, becomes more common with older age, and can appear in other autoimmune conditions, such as Sjögren's syndrome, as well as during some persistent infections. As a rough guide, around 1 in 20 people without rheumatoid arthritis will also test positive for rheumatoid factor.
So a positive rheumatoid factor on its own does not mean you have rheumatoid arthritis. It is one piece of information, weighed alongside your symptoms, the examination findings and the other results, never read in isolation.
Anti-CCP, and what a positive result means
Anti-CCP is more specific for rheumatoid arthritis than rheumatoid factor, which means a positive anti-CCP points more reliably towards the condition and is less likely to appear in people without it. It can also help identify rheumatoid arthritis early, before the pattern is fully established, and is useful in distinguishing it from other causes of joint pain.
Because it is more specific, a positive anti-CCP carries more weight than a positive rheumatoid factor, and people who are positive for both tests are more likely to have a clear-cut and potentially more active form of the disease. Even so, anti-CCP is interpreted within the whole picture: it raises the likelihood of rheumatoid arthritis rather than proving it by itself, and what matters is how it fits with your symptoms and examination.
Negative tests do not rule it out
Just as a positive test does not confirm rheumatoid arthritis, a negative one does not exclude it. Some people have genuine rheumatoid arthritis with normal rheumatoid factor and anti-CCP results. This is known as seronegative rheumatoid arthritis, and it is a real and recognised form of the condition.
This is why the diagnosis is never made, or dismissed, on the strength of these antibodies alone. If the joints are inflamed and the clinical picture fits, rheumatoid arthritis can be diagnosed and treated even when both tests are negative.
Why the whole picture matters more than any single test
Because neither test confirms nor excludes the diagnosis on its own, the assessment rests on bringing everything together: a careful history, an examination of the joints, the inflammation and antibody results, and, where helpful, ultrasound. Ultrasound is particularly valuable, because it can show inflammation in the joint lining, known as synovitis, sometimes before damage has occurred and before the joints look visibly swollen.
Dr Borukhson uses point-of-care ultrasound during the consultation itself, so the question these antibody tests raise can usually be settled in a single visit: either reassurance that no inflammatory arthritis is evident, or a clear diagnosis and a treatment plan agreed with you. You can read more on the point-of-care ultrasound page, and about the wider panel on the understanding blood tests page.
Where rheumatoid arthritis is confirmed, there is a real benefit to starting treatment promptly, as early treatment gives the best chance of protecting the joints. This is a reason to seek a timely assessment when symptoms persist, not a cause for alarm. You can read more on the rheumatoid arthritis page.
When assessment is worthwhile
If you have been told your rheumatoid factor or anti-CCP is positive but you feel well, there is usually no need for alarm, though a specialist review can settle what the result means in the context of your own health. An assessment is particularly worthwhile if a result comes alongside symptoms such as:
- Pain and swelling in several joints, often the small joints of the hands and feet
- Joint stiffness in the morning that lasts more than half an hour
- Joints that feel warm, tender or swollen
- Persistent tiredness or a general sense of being unwell
If you feel significantly unwell, contact your GP or NHS 111 rather than waiting for a routine appointment.
Common questions
I have been told my rheumatoid factor is positive. Does that mean I have rheumatoid arthritis?
Not on its own. A positive rheumatoid factor is fairly common, becomes more likely with older age, and can appear in healthy people as well as in other conditions, so it is only one piece of the picture. What matters is how the result fits with your symptoms, the examination of your joints and the other tests. A specialist review can settle what a positive result actually means for you.
Can these blood tests confirm or rule out rheumatoid arthritis by themselves?
No. Neither rheumatoid factor nor anti-CCP confirms rheumatoid arthritis on its own, and a negative result does not exclude it, because some people have genuine disease with normal antibodies. The tests are always read alongside your history, an examination and markers of inflammation. Ultrasound adds a further layer, as it can show inflammation in the joint lining before the joints look visibly swollen.
What is the difference between rheumatoid factor and anti-CCP?
Both are antibodies measured in the blood and are often requested together when an inflammatory arthritis is being considered. Rheumatoid factor is the older test and is less specific, meaning it can also show up in people without rheumatoid arthritis. Anti-CCP is more closely tied to rheumatoid arthritis, so a positive result points more reliably towards it, though it still needs to be interpreted within the whole clinical picture.
If my tests are positive but I feel well, do I need to do anything?
If you feel well, there is usually no need for alarm, but a specialist review can explain what the result means in the context of your own health. An assessment is particularly worthwhile if the result comes alongside joint pain or swelling, morning stiffness lasting more than half an hour, or a general sense of being unwell. Dr Borukhson uses point-of-care ultrasound during the consultation, so the question these tests raise can often be settled in a single visit, with either reassurance or a clear plan.
Told your rheumatoid factor or anti-CCP is positive?
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