en Reumatology Reumatology Original Article Original Article <span style="font-size:14px;"><span style="font-family:times new roman;"><span style="color:#0000FF;"><strong><em>Background</em></strong><em>:</em></span> The present study aimed to evaluate serum YKL-40 levels in patients with rheumatoid arthritis (RA) compared to healthy subjects and to search whether there is an association between YKL-40 levels and disease characteristics in RA.<br> <span style="color:#0000FF;"><strong><em>Methods</em></strong><em>:</em></span> In this cross-sectional study, 60 RA patients based on the ACR/EULAR 2010 criteria and 30 age- and sex-matched healthy controls were included. In patients, clinical examination was performed and disease activity score 28 (DAS-28) measure of disease activity was assessed. Serum YKL-40 level was measured using ELISA kit.<br> <span style="color:#0000FF;"><strong><em>Results</em></strong><em>:</em> </span>The mean&plusmn;SD age of patients and controls was 54.86&plusmn;11.65 and 50.71&plusmn;3.72 years, respectively). Serum YKL-40 level was significantly higher in RA patients (951.63&plusmn;639.98 pg/mL) compared to healthy controls (444.92&plusmn;150.37 pg/mL) (P<0.001). There was no significant difference in serum YKL-40 level according to the activity of disease (p>0.05). There were significant positive correlations between serum YKL-40 level with disease activity (r=0.347, P=0.007) and rheumatoid factor (r=0.396, P=0.002). There were no significant correlations between serum YKL-40 level with demographic characteristics as well as biochemical measurements including serum creatinine, blood urea nitrogen, erythrocyte sedimentation rate, C-reactive protein and anti-cyclic citrullinated peptide.<br> <span style="color:#0000FF;"><strong><em>Conclusion</em></strong><em>:</em></span> Our study revealed higher serum YKL-40 levels in RA patients compared to healthy controls, which correlated positively with disease activity. Therefore, YKL-40 can be considered as a novel biomarker for disease activity estimation in RA.</span></span> Rheumatoid arthritis, YKL-40, Disease activity. 92 97 http://caspjim.com/browse.php?a_code=A-10-1130-1&slc_lang=en&sid=1 Mohammad Reza Jafari-Nakhjavani drmrjn@yahoo.com 100319475328460015051 100319475328460015051 No Connective Tissue Diseases Research Center, Tabriz University of Medical Sciences, Tabriz, Iran Amir Ghorbanihaghjo ghorbaniamir@hotmail.com 100319475328460015052 100319475328460015052 No Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran Babak Bagherzadeh-Nobari connectivetrc@gmail.com 100319475328460015053 100319475328460015053 No Connective Tissue Diseases Research Center, Tabriz University of Medical Sciences, Tabriz, Iran Aida Malek-Mahdavi aidamalek@gmail.com 100319475328460015054 100319475328460015054 Yes Connective Tissue Diseases Research Center, Tabriz University of Medical Sciences, Tabriz, Iran Nadereh Rashtchizadeh rashtchizadeh@rocketmail.com 100319475328460015055 100319475328460015055 No Connective Tissue Diseases Research Center, Tabriz University of Medical Sciences, Tabriz, Iran