Rheumatology International

, Volume 33, Issue 2, pp 341–346

Relationship between sonographic parameters and YKL-40 levels in rheumatoid arthritis


  • Maria Kazakova
    • Department of Medical BiologyMedical University-Plovdiv
  • Anastas Batalov
    • Department of RheumatologyMedical University-Plovdiv
  • Tanya Deneva
    • Department of Clinical LaboratoryMedical University-Plovdiv
  • Nonka Mateva
    • Department of Health Management, Health Economics and General MedicineMedical University-Plovdiv
  • Zlatimir Kolarov
    • Clinic of RheumatologyMedical University-Sofia
    • Department of Medical BiologyMedical University-Plovdiv
Original Article

DOI: 10.1007/s00296-012-2387-3

Cite this article as:
Kazakova, M., Batalov, A., Deneva, T. et al. Rheumatol Int (2013) 33: 341. doi:10.1007/s00296-012-2387-3


YKL-40, also known as human cartilage glycoprotein 39, is a member of the “mammalian chitinase-like proteins” family without chitinase activity. Increased serum concentrations are associated with inflammatory processes and several types of cancer. In this study, we evaluated YKL-40 levels in serum and synovial fluid of patients with rheumatoid arthritis in comparison with the ultrasonographic findings. YKL-40 levels were measured by enzyme-linked immunosorbent assay in 25 patients with active rheumatoid arthritis and in 40 healthy subjects. B mode and power Doppler were performed to determine synovial thickening and vascularization. Serum YKL-40 level in patients was significantly higher than the concentration in healthy controls (P < 0.01). In patients with rheumatoid arthritis, the level of the glycoprotein in synovial fluid was remarkably elevated compared to the serum level (P = 0.003). The B mode and power Doppler scores correlated to YKL-40 in serum and synovial fluid (P = 0.07). Serum YKL-40 levels were related positively to serum markers of inflammation such as C-reactive protein (P = 0.004) and erythrocyte sedimentation rate (P = 0.003). This study is the first to demonstrate a relationship between YKL-40 levels and ultrasonographic examinations in Bulgarian patients with rheumatoid arthritis. The findings suggest that YKL-40 might be implicated in the pathogenesis of the disease and could indicate the level of joint inflammation.


Joint sonographyYKL-40Rheumatoid arthritis

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© Springer-Verlag 2012