title: Serum YKL-40 levels in rheumatoid arthritis: correlations between clinical and laborarory parameters.
abstract: OBJECTIVE
  To clarify the significance of YKL-40, also called human cartilage glycoprotein-39, in the serum of patients with RA, we studied serum YKL-40 in relation to clinical and laboratory parameters.
  
  
  METHODS
  Seventy-two patients (16 men and 56 women) with RA and 40 age-matched healthy persons (14 men, 26 women) were included in this study. Serum levels of YKL-40, insulin-like growth factor-I (IGF-I) and interleukin-6 (IL-6) were measured by ELISA. Radiological changes reflecting joint destruction and the joint score for pain or swelling were assessed by taking into account the joint surface area. Serum CRP levels and the functional disability of patients were also determined.
  
  
  RESULTS
  YKL-40 levels in the serum of patients with RA were significantly higher than those of controls (p < 0.0001), and showed positive correlations with serum levels of IL-6 (r = 0.301, p = 0.011) and CRP (r = 0.326, p = 0.006), but negative correlations with serum levels of IGF-I (r = -0.340, p = 0.004). The radiological score, but not joint pain, also correlated with YKL-40 levels (r = 0.364, p = 0.002). As the functional disability of patients became severe, the serum YKL levels increased.
  
  
  CONCLUSIONS
  Serum YKL-40 levels partially reflect the degree of inflammation and also reflect the joint destruction in patients with RA.
authors.affiliation: Department of Orthopedic Surgery, Nagasaki University, School of Medicine, Japan. tomoko-m@net.nagasaki-u.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Matsumoto
authors.forename: T
authors.initials: T
authors.lastname: Tsurumoto
mesh_terms: D054392:Adipokines; D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000097:blood* / Q000000981:diagnostic imaging / Q000503:physiopathology; D001175:Arthrography; D001324:Autoantigens / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D000071451:Chitinase-3-Like Protein 1; D005260:Female; D006023:Glycoproteins / Q000097:blood*; D006133:Growth Substances / Q000097:blood*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D015850:Interleukin-6 / Q000097:blood; D007596:Joints / Q000473:pathology / Q000503:physiopathology; D037102:Lectins; D008297:Male; D008875:Middle Aged; D012720:Severity of Illness Index
chemical_list: D054392:Adipokines; D001324:Autoantigens; D015415:Biomarkers; C084533:CHI3L1 protein, human; D000071451:Chitinase-3-Like Protein 1; D006023:Glycoproteins; D006133:Growth Substances; D015850:Interleukin-6; D037102:Lectins; D007334:Insulin-Like Growth Factor I