title: Increased urinary N-telopeptide cross-linked type 1 collagen predicts bone loss in patients with inflammatory bowel disease.
abstract: OBJECTIVE
  Reduced bone mineral density (BMD) is common in patients with inflammatory bowel disease (IBD), but the factors associated with its longitudinal rate of change have not been established. We prospectively assessed the rate of change in BMD, and its association with biochemical markers of bone turnover.
  
  
  METHODS
  Twenty-two patients with Crohn's disease and 14 ulcerative colitis patients age 37.1 +/- 11.6 yr were followed for 2 yr. Lumbar spine (L2-L4) and femoral neck BMD were measured by dual x-ray absorptiometry at baseline and 24 months. Bone-specific alkaline phosphatase, osteocalcin, urinary N-telopeptide crosslinked type 1 collagen (NTx), parathyroid hormone, and 25-hydroxyvitamin-D were determined at baseline.
  
  
  RESULTS
  At baseline, 59% of Crohn's patients and 43% of ulcerative colitis patients were osteoporotic, with spine or femoral neck BMD T-score < -2.5. Spine BMD, and spine and femoral neck T-scores were lower and disease duration was longer in nine patients with ileal resection compared with nonoperated patients (0.84 +/- 0.15 g/cm2 vs 0.96 +/- 0.11 g/cm2, -3.0 +/- 1.5 vs -1.7 +/- 1.3, -3.2 +/- 1.5 vs -2.2 +/- 1.0, respectively; all p < 0.05). At 24 months, 13/36 (36%) and 14/36 (39%) patients experienced spinal and femoral neck bone loss, respectively, with mean annual percent BMD changes of -2.0% and -1.5%, respectively. NTx, a bone resorption marker, inversely correlated with spinal BMD rate of change (r = -0.4, p < 0.05). Using quartiles analysis, patients with the highest NTx (Q4) experienced the greatest decrease in spine BMD compared with patients with the lowest NTx (Q1).
  
  
  CONCLUSIONS
  Spine and femoral neck bone loss continues over time in more than one-third of IBD patients. Increased NTx level predicts spinal bone loss in IBD patients.
authors.affiliation: Department of Medicine, Hadassah University Hospital on Mount Scopus, Hebrew University Hadassah Medical School, Jerusalem, Israel.
authors.forename: R
authors.initials: R
authors.lastname: Dresner-Pollak
authors.forename: F
authors.initials: F
authors.lastname: Karmeli
authors.forename: R
authors.initials: R
authors.lastname: Eliakim
authors.forename: Z
authors.initials: Z
authors.lastname: Ackerman
authors.forename: D
authors.initials: D
authors.lastname: Rachmilewitz
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D015519:Bone Density / Q000502:physiology*; D001862:Bone Resorption / Q000175:diagnosis / Q000652:urine; D003093:Colitis, Ulcerative / Q000175:diagnosis* / Q000652:urine; D003094:Collagen / Q000652:urine*; D024042:Collagen Type I; D003424:Crohn Disease / Q000175:diagnosis* / Q000652:urine; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000175:diagnosis* / Q000652:urine; D010455:Peptides / Q000652:urine*
chemical_list: D024042:Collagen Type I; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D003094:Collagen