title: Serum leucine-rich α2-glycoprotein is a useful biomarker for monitoring disease activity in patients with adult-onset Still's disease.
abstract: OBJECTIVE
  To investigate whether serum leucine-rich α2-glycoprotein (LRG) levels are elevated in patients with adult-onset Still's disease (AOSD) and determine their correlation with disease activity parameters.
  
  
  METHODS
  We enrolled 39 patients with AOSD, 47 patients with rheumatoid arthritis (RA), and 39 controls. Forty-five serum samples from the patients with AOSD were assayed for LRG using an enzyme-linked immunosorbent assay (ELISA). Comprehensive AOSD activity was determined by a modified Pouchot score.
  
  
  RESULTS
  Serum LRG levels were significantly elevated in patients with AOSD (128.8±40.8 ng/mL) compared to those in patients with RA and in controls (33.9±15.2 ng/mL, p<0.001 and 22.4±6.1 ng/mL, p<0.001, respectively). Patients with active AOSD had significantly higher LRG levels than those with inactive disease (141.4±31.3 ng/mL vs. 79.8±37.1 ng/mL, p=0.002). Serum LRG levels were positively correlated with C-reactive protein (CRP; γ=0.387, p=0.015), lactate dehydrogenase (LDH; γ=0.370, p=0.026), ferritin (γ=0.687, p<0.001) levels, and the modified Pouchot score (γ=0.756, p<0.001). Serum LRG levels decreased significantly after treatment in all six patients with active AOSD who had follow-up evaluations (p=0.007). The best cut-off value for LRG to distinguish AOSD from RA was 67.9 ng/mL, with a sensitivity of 92.3% and a specificity of 97.9%.
  
  
  CONCLUSIONS
  Serum LRG levels were increased in patients with AOSD and correlated well with disease activity measures. LRG may be a useful biomarker for distinguishing AOSD from RA and for monitoring the disease activity of AOSD.
authors.affiliation: a Division of Rheumatology, Department of Internal Medicine , Seoul National University Bundang Hospital , Gyeonggi , South Korea.
authors.forename: Y-J
authors.initials: YJ
authors.lastname: Ha
authors.affiliation: b Division of Rheumatology, Department of Internal Medicine , Busan Medical Centre , Busan , South Korea.
authors.forename: E-J
authors.initials: EJ
authors.lastname: Kang
authors.affiliation: c Division of Rheumatology, Department of Internal Medicine , Yonsei University College of Medicine , Seoul , South Korea.
authors.forename: S-W
authors.initials: SW
authors.lastname: Lee
authors.affiliation: c Division of Rheumatology, Department of Internal Medicine , Yonsei University College of Medicine , Seoul , South Korea.
authors.forename: Y-B
authors.initials: YB
authors.lastname: Park
authors.affiliation: c Division of Rheumatology, Department of Internal Medicine , Yonsei University College of Medicine , Seoul , South Korea.
authors.forename: S-K
authors.initials: SK
authors.lastname: Lee
authors.affiliation: d Division of Rheumatology, Department of Internal Medicine , Chung-Ang University College of Medicine , Seoul , South Korea.
authors.forename: J-S
authors.initials: JS
authors.lastname: Song
authors.affiliation: d Division of Rheumatology, Department of Internal Medicine , Chung-Ang University College of Medicine , Seoul , South Korea.
authors.forename: S T
authors.initials: ST
authors.lastname: Choi
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000378:metabolism; D016022:Case-Control Studies; D018450:Disease Progression; D005260:Female; D005293:Ferritins / Q000097:blood; D006023:Glycoproteins / Q000097:blood*; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000097:blood; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D016706:Still's Disease, Adult-Onset / Q000097:blood / Q000175:diagnosis*
chemical_list: D015415:Biomarkers; D006023:Glycoproteins; C015246:LRG1 protein, human; D002097:C-Reactive Protein; D005293:Ferritins; D007770:L-Lactate Dehydrogenase