CRP and rheumatoid arthritis: At the time of RA diagnosis, her rheumatoid factor (RF) titer was 21 IU/mL (normal range, ≤ 14 IU/mL), anti-cyclic citrullinated peptide titer was 0.4 U/mL (normal range, ≤ 5 U/mL), C-reactive protein (CRP) level was 0.85 mg/dL (normal range, ≤ 0.5 mg/dL), and erythrocyte sedimentation rate (ESR) was 56 mm/h (normal range, ≤ 25 mm/h).