We take great care to make sure that the information in this leaflet is correct and up-to-date. However, medicines can be used in different ways for different patients. It is important that you ask the advice of your doctor or pharmacist if you are not sure about something. This leaflet is about the use of these medicines in the UK, and may not apply to other countries. The Royal College of Paediatrics and Child Health (RCPCH), the Neonatal and Paediatric Pharmacists Group (NPPG), WellChild and the contributors and editors cannot be held responsible for the accuracy of information, omissions of information, or any actions that may be taken as a consequence of reading this leaflet.
Abnormal antibodies can be found in the blood of people with rheumatoid arthritis with simple blood testing. An antibody called "rheumatoid factor" (RF) can be found in 80% of patients with rheumatoid arthritis. Patients with rheumatoid arthritis and rheumatoid factor are referred to as having "seropositive rheumatoid arthritis." Patients who are felt to have rheumatoid arthritis and do not have positive rheumatoid factor testing are referred to as having "seronegative rheumatoid arthritis." Citrulline antibody (also referred to as anti-citrulline antibody, anticyclic citrullinated peptide antibody, and anti-CCP antibody) is present in 50%-75% people with rheumatoid arthritis. It is useful in the diagnosis of rheumatoid arthritis when evaluating cases of unexplained joint inflammation. A test for citrulline antibodies is especially helpful in looking for the cause of previously undiagnosed inflammatory arthritis when the traditional blood test for rheumatoid arthritis, rheumatoid factor, is not present. Citrulline antibodies have been felt to represent the earlier stages of rheumatoid arthritis in this setting. Citrulline antibodies also have been associated with more aggressive forms of rheumatoid arthritis. Another antibody called the "antinuclear antibody" (ANA) is also frequently found in people with rheumatoid arthritis.