CRP and rheumatoid arthritis: For example, patients with rheumatoid arthritis usually have persistently elevated CRP levels, with baseline CRP levels often exceeding 20 mg/L in randomized clinical trials of drugs for rheumatoid arthritis [16], however, retrospective and observational studies have found that many patients with rheumatoid arthritis have normal CRP levels despite exhibiting disease activity, suggesting that CRP levels only reflect signs of disease activity [27, 28].