title: Serum B2-microglobulin concentration correlates with urinary concentrations of type 1 collagen cross-linked N-telopeptides and deoxypyridinoline in rheumatoid arthritis.
abstract: BACKGROUND
  Determination of serum ss2-microglobulin concentration, an invasive procedure, has been advocated for monitoring patientsA centAA response to treatment in rheumatoid arthritis. The object of this study was to find out if serum ss2-microglobulin concentration correlated with urinary excretions of type 1 collagen crosslinked N-telopeptides (NTx) and deoxypyridinoline (Pyrilinks-D) in rheumatoid arthritis (RA).
  
  
  METHODS
  Using chemiluminiscent assay, serum ss2-microglobulin concentrations were estimated in 25 female patients with active RA, 25 female with inactive disease, and 25 age-matched healthy female controls. Concentrations of NTx and Pyrilinks-D were also determined by immunoabsorbent assays in spot urine samples from these subject groups.
  
  
  RESULTS
  The serum concentration of ss2-microglobulin in patients with RA (7.45+/-2.10 mg/L) was significantly higher (P<0.001) than the concentrations in patients with inactive disease (3.33+/-0.76 mg/L), or than in normal healthy controls (2.747plusmn;0.52 mg/L). Similarly, in patients with active RA, the spot urinary concentrations of NTx (123.08+/-25.53 nmol BCE/mmol creatinine) and Pyrilinks-D (15.087plusmn;3.29 nmol/mmol creatinine) were significantly higher (P<0.01) than those in patients with inactive disease (58.42AA+/-12.65 nmol BCE/mmol creatinine and 10.10+/-2.43 nmol/mmol creatinine, respectively). In patients with active RA, serum concentration of ss2-microglobulin correlated positively with spot urinary NTx concentrations (r=0.9910, P=0.0001), and Pyrilinks-D concentration (r=0.6177, P=0.001).
  
  
  CONCLUSIONS
  In patients with active RA, the spot urinary concentrations of NTx and Pyrilinks-D correlated positively with serum AA2-microglobulin. Therefore, the estimations of these urinary markers may take the place of serum ss2-microglobulin estimation in monitoring the patientA centAAs response to treatment in rheumatoid arthritis.
authors.affiliation: Departments of Medicine, Rheumatology Unit, Pathology, and Physiology, Faculty of Medicine, Kuwait University, Safat, Kuwait.
authors.forename: A
authors.initials: A
authors.lastname: Al-Awadi
authors.forename: S O
authors.initials: SO
authors.lastname: Olusi
authors.forename: N
authors.initials: N
authors.lastname: Al-Zaid
authors.forename: K
authors.initials: K
authors.lastname: Prabha