A 45-year-old woman presents with symmetric polyarthritis of MCP and PIP joints lasting 8 weeks. Rheumatoid factor is negative. Which serological test has the highest specificity for diagnosing rheumatoid arthritis in this patient?

• A Anti-nuclear antibody (ANA)
• B C-reactive protein (CRP)
• C Anti-cyclic citrullinated peptide (anti-CCP) antibody ✓
• D Erythrocyte sedimentation rate (ESR)

Explanation

Anti-CCP antibody has 95-98% specificity for RA compared to 85% for RF. It is present in 60-70% of RF-negative RA patients and helps confirm diagnosis. Anti-CCP positivity also predicts erosive disease progression. ANA, CRP, and ESR are nonspecific markers of inflammation.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.