title: Evaluation of serum beta-carboxy-terminal cross-linking telopeptide of type I collagen as marker of bone resorption in chronic hemodialysis patients.
abstract: BACKGROUND
  The carboxy-terminal cross-linking telopeptide of type I collagen (beta-CrossLaps, beta-CTX) is released into the circulation during degradation of type I collagen and serves as a marker of bone resorption. beta-CTX is known to undergo a diurnal rhythm in normal individuals and to accumulate in chronic renal failure. beta-CTX has a potential role in noninvasive diagnosis of renal bone disease.
  
  
  METHODS
  Serum beta-CTX was compared to parathyroid hormone (PTH) and other biochemical bone markers in 90 unselected hemodialysis patients.
  
  
  RESULTS
  Mean beta-CTX was elevated above the normal range (1.72 +/- 0.93 microg/l); there were large individual variations. Serum beta-CTX was significantly correlated with various PTH assays (r >0.56) and with tartrate-resistant acid phosphatase 5b (TRACP 5b, r = 0.629), bone-specific alkaline phosphatase (r = 0.404) and osteocalcin (r = 0.534, all correlations p < 0.001). The correlation between beta-CTX and PTH was significantly higher than the correlation between TRACP 5b and PTH. Several factors which could confound interpretation of serum beta-CTX were assessed in further studies: (i) There was no recognizable influence of the time of blood sampling (morning dialysis shift versus afternoon dialysis shift) on serum beta-CTX. (ii) Serum beta-CTX was not significantly related to residual diuresis of patients.
  
  
  CONCLUSIONS
  We found a high association between beta-CTX and other established markers of bone and calcium metabolism demonstrating the potential utility of beta-CTX as marker of bone resorption in renal bone disease. However, further studies employing bone histology are still warranted to exactly define the influence of glomerular retention on serum beta-CTX in end-stage renal disease.
authors.affiliation: Nephrological Center, Villingen-Schwenningen, Germany. Helmut.Reichel@dialyse-schwenningen.de
authors.forename: Helmut
authors.initials: H
authors.lastname: Reichel
authors.forename: Heinz-Jürgen
authors.initials: HJ
authors.lastname: Roth
authors.forename: Heinrich
authors.initials: H
authors.lastname: Schmidt-Gayk
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D001862:Bone Resorption / Q000097:blood* / Q000175:diagnosis* / Q000209:etiology; D003094:Collagen / Q000097:blood*; D024042:Collagen Type I; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000150:complications* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D010455:Peptides / Q000097:blood*; D006435:Renal Dialysis
chemical_list: D015415:Biomarkers; D024042:Collagen Type I; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D003094:Collagen