Previous studies showed that serum calprotectin levels were correlated with disease activity and can predict therapy response in patients with RA.17–19 Several studies have described that calprotectin was better than CRP in indicating inflammation detected by ultrasound.20–22 However, there is limited evidence regarding the importance of calprotectin in indicating activity in RA patients with normal CRP levels.21 There is a need for a simple and rapid biomarker that accurately demonstrates disease activity and inflammation in RA patients. This evidence concerns the gene CRP and rheumatoid arthritis.