Which statement about serology is typical for rheumatoid arthritis?

• A. RA often has positive RF or anti-CCP antibodies
• B. RF and anti-CCP antibodies are always negative
• C. Anti-CCP is never positive in RA
• D. RF and anti-CCP antibodies are never helpful in RA

Answer: (C)

Rheumatoid arthritis typically shows autoantibodies in the blood, mainly rheumatoid factor and anti-CCP antibodies. Anti-CCP antibodies have very high specificity for RA, so a positive test strongly supports the diagnosis, especially when joint symptoms are present. RF is also commonly positive but is less specific, because it can occur in other diseases and even in some healthy older individuals. Because of this, many patients with RA are seropositive for RF or anti-CCP, and some patients may be seronegative. The idea that anti-CCP is never positive in RA is not correct; in fact, anti-CCP positivity is a hallmark of RA in many cases.