title: Serum concentrations of interleukin 6, osteocalcin, intact parathyroid hormone, and markers of bone resorption in patients with rheumatoid arthritis.
abstract: OBJECTIVE
  To analyze serum concentrations of interleukin 6 (IL-6), osteocalcin, intact parathyroid hormone (PTH), and type 1 collagen carboxyterminal telopeptide (ICTP) as well as the urinary concentrations of crosslinked N-telopeptides of type 1 collagen (NTx) and deoxypyridinoline (Dpd) in patients with rheumatoid arthritis (RA) to investigate their role in the etiology of the osteopenia in this disease.
  
  
  METHODS
  Using ELISA and radioimmunoassay methods, we estimated serum concentrations of IL-6, osteocalcin, ICTP, intact PTH, and spot urine concentrations of NTx and Dpd in 25 female patients with active RA, 25 female patients with suppressed disease, and 25 age matched healthy female controls.
  
  
  RESULTS
  Patients with active RA had significantly higher (p < 0.001) concentrations of IL-6 (94.0+/-12.1 pg/ml) compared to patients with suppressed disease (13.2+/-0.8 pg/ml) and healthy controls (12.3+/-0.8 pg/ml). Serum osteocalcin was significantly lower (p < 0.001) in patients with active RA (1.9+/-0.2 ng/ml) compared to patients with suppressed disease (2.7+/-0.2 ng/ml) and the controls (2.9+/-0.2 ng/ml). Similarly, serum intact PTH was significantly lower (p < 0.001) in patients with active disease (29.9+/-1.5 ng/ml) compared to patients with suppressed RA (38.0+/-1.6 ng/ml) and controls (49.8+/-2.4 ng/ml). Serum ICTP was also significantly higher (p < 0.01) in patients with active RA (9.5+/-0.3 microg/l) versus patients with suppressed disease (4.1+/-0.2 microg/l) and controls (3.4+/-0.2 microg/l). In patients with active disease, spot urine concentrations of NTx (123.1+/-5.1 nmol bone collagen equivalent/mmol creatinine) and Dpd (15.1+/-0.7 nmol/mmol creatinine) were significantly higher (p < 0.001) than in patients with suppressed disease (58.4+/-2.5 nmol bone collagen equivalent/mmol creatinine and 10.1+/-0.5 nmol/mmol creatinine, respectively) and healthy controls (53.4+/-2.1 nmol bone collagen equivalent/mmol creatinine and 9.7+/-0.5 nmol/mmol creatinine, respectively). There were no significant correlations between serum IL-6 and serum ICTP (r = 0.2357, p = 0.257) or urinary NTx (r = 0.1436, p = 0.494) or between serum intact PTH and ICTP (r = 0.0206, p = 0.922) in patients with active RA.
  
  
  CONCLUSIONS
  There are no significant correlations between bone resorption markers and serum IL-6 and intact PTH in patients with RA.
authors.affiliation: Department of Medicine, Faculty of Medicine, Kuwait University, Al-Safat.
authors.forename: A
authors.initials: A
authors.lastname: Al-Awadhi
authors.forename: S
authors.initials: S
authors.lastname: Olusi
authors.forename: N
authors.initials: N
authors.lastname: Al-Zaid
authors.forename: K
authors.initials: K
authors.lastname: Prabha
mesh_terms: D000328:Adult; D000596:Amino Acids / Q000652:urine; D001172:Arthritis, Rheumatoid / Q000097:blood* / Q000150:complications; D015415:Biomarkers / Q000097:blood / Q000652:urine; D001851:Bone Diseases, Metabolic / Q000097:blood / Q000150:complications / Q000652:urine; D001862:Bone Resorption / Q000097:blood* / Q000378:metabolism / Q000652:urine; D003094:Collagen / Q000097:blood / Q000652:urine; D024042:Collagen Type I; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D008875:Middle Aged; D015675:Osteocalcin / Q000097:blood*; D010281:Parathyroid Hormone / Q000097:blood*; D010455:Peptides / Q000097:blood / Q000652:urine
chemical_list: D000596:Amino Acids; D015415:Biomarkers; D024042:Collagen Type I; D015850:Interleukin-6; D010281:Parathyroid Hormone; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D015675:Osteocalcin; C036020:deoxypyridinoline; D003094:Collagen