Rosh Internal Medicine Boost Practice Exam

What confirms the diagnosis of rheumatoid arthritis?

1. Presence of anti-nuclear antibodies

2. Positive rheumatoid factor alone

3. Positive anticitrullinated protein antibodies

4. Joint effusion analysis

The correct answer is: Positive anticitrullinated protein antibodies

The confirmation of a rheumatoid arthritis diagnosis relies heavily on specific antibody tests that reflect the autoimmune process characteristic of the disease. The presence of anticitrullinated protein antibodies (ACPAs), specifically anti-citrullinated cyclic peptide (anti-CCP) antibodies, serves as a highly specific biomarker for rheumatoid arthritis. These antibodies are present in a significant proportion of patients and correlate with disease severity. Their detection not only aids in the diagnosis but also implies a more aggressive disease course, making them a critical component in confirming rheumatoid arthritis. While the presence of other antibodies, such as rheumatoid factor or anti-nuclear antibodies, can provide supportive evidence for a diagnosis, they lack the specificity that ACPAs provide. Joint effusion analysis may offer insight into synovial fluid characteristics but does not directly confirm the autoimmune nature of rheumatoid arthritis. Thus, the presence of ACPAs is a definitive factor in establishing this condition.