title: Early changes in bone mass, biochemical bone markers and fibroblast growth factor 23 after renal transplantation.
abstract: BACKGROUND
  Serum osteocalcin and C-terminal telopeptides of type-1 collagen (CTX-1) are known markers of bone turnover, whereas the role of fibroblast growth factor 23 (FGF-23) is yet unknown. We investigated early changes in bone mass and the association of these biochemical markers and FGF-23 with bone loss following renal transplantation (RTx).
  
  
  METHODS
  In 44 first-kidney allograft patients, BMD was measured by dual-energy X-ray absorptiometry in the lumbar spine (LS), total femur (TF) and total body (TB) at baseline and 10 weeks post-transplant. Serum osteocalcin, CTX-1, intact FGF-23, intact parathormone (iPTH) and 25-hydroxyvitamin D (25-OHD) levels were measured. Associations were tested by correlation and multiple linear regression.
  
  
  RESULTS
  We found a significant (p<0.05) decrease in bone mass in LS (2.6 %), TF (2.1 %) and TB (1.4 %). Osteocalcin (0.95 versus 1.56 nmol/L) and CTX-1 (1.05 versus 1.47 ng/mL) levels increased significantly, while serum FGF-23 and iPTH decreased. Serum osteocalcin and CTX-1 were significantly associated at both baseline and follow-up. Baseline osteocalcin and CTX-1 were independently associated with bone loss in TB and TF, respectively. Neither iPTH nor 25-OHD showed consistent association with bone loss. FGF-23 was not related to change in bone mass or to biochemical markers of bone turnover.
  
  
  CONCLUSIONS
  Our results confirm an early decrease in bone mass with high bone resorption rate after RTx. Osteocalcin and CTX-1 are associated with bone loss in the early post-transplant period; thus, these markers may be a reasonable choice for routine assessment of bone turnover in this setting. The role of FGF-23 remains to be further elucidated.
authors.affiliation: Medical Center, Rikshospitalet-Radiumhospitalet, University of Oslo, Oslo, Norway. szilveszter.dolgos@rikshospitalet.no
authors.forename: Szilveszter
authors.initials: S
authors.lastname: Dolgos
authors.forename: Anders
authors.initials: A
authors.lastname: Hartmann
authors.forename: Stine
authors.initials: S
authors.lastname: Bønsnes
authors.forename: Gunhild Aker
authors.initials: GA
authors.lastname: Isaksen
authors.forename: Kristin
authors.initials: K
authors.lastname: Godang
authors.forename: Thor
authors.initials: T
authors.lastname: Ueland
authors.forename: Per
authors.initials: P
authors.lastname: Pfeffer
authors.forename: Jens
authors.initials: J
authors.lastname: Bollerslev
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood*; D015519:Bone Density; D001842:Bone and Bones / Q000378:metabolism*; D024042:Collagen Type I / Q000097:blood; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D006801:Humans; D007166:Immunosuppressive Agents / Q000008:administration & dosage; D016030:Kidney Transplantation; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D015675:Osteocalcin / Q000097:blood; D010281:Parathyroid Hormone / Q000097:blood; D010455:Peptides / Q000097:blood; D011446:Prospective Studies; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood
chemical_list: D015415:Biomarkers; D024042:Collagen Type I; C000717427:FGF23 protein, human; D007166:Immunosuppressive Agents; D010281:Parathyroid Hormone; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D015675:Osteocalcin; D014807:Vitamin D; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23; C104450:25-hydroxyvitamin D