title: Early rapid loss followed by long-term consolidation characterizes the development of lumbar bone mineral density after kidney transplantation.
abstract: BACKGROUND
  Bone mineral density (BMD) decreases significantly early after renal transplantation. This prospective study was designed to evaluate the long-term lumbar BMD development.
  
  
  METHODS
  Sixty-three renal-transplant recipients (mean age 44 +/- 12 years, 37 [59%] male) underwent serial yearly posttransplant laboratory parameter and BMD measurements of the lumbar spine (dual energy x-ray absorptiometry). Combined maintenance immunosuppression included prednisolone in 95% of patients. The minimum number of consecutive scans was three; the maximum number seven (n = 15). Examinations were performed between 3 +/- 2 and 68 +/- 4 months posttransplant.
  
  
  RESULTS
  BMD was significantly lower compared with healthy controls at all times after transplantation. t scores were below -1. BMD development revealed a biphasic pattern: between 3 +/- 2 and 10 +/- 2 months, a significant BMD decrease of -0.016 +/- 0.055 g/cm2 (-1.6%, P = 0.024) occurred. Later, a moderate increase resulting in BMD stability until the sixth year posttransplant was detected. Within the first year, posttransplant osteocalcin (from 19 +/- 15 to 32 +/- 23 microg/L) and calcitriol (from 24 +/- 15 to 43 +/- 24 ng/L) displayed a significant increase. Compared with patients with a pronounced decrease, patients with a substantial increase in early posttransplant BMD had a lower baseline BMD (0.989 +/- 0.131 vs. 1.149 +/- 0.202 g/cm2 [P = 0.0122]) and lower creatinine levels (105 +/- 23 vs. 141 +/- 53 mmol/L [P = 0.0227]).
  
  
  CONCLUSIONS
  Our study confirms a significant decrease of lumbar BMD early after renal transplantation. Bone loss was less pronounced than previously described. The longitudinal follow-up verifies a previously assumed biphasic lumbar BMD development: after the first year, no further significant bone loss occurred, and bone density remained relatively stable at significantly lower levels compared with healthy controls.
authors.affiliation: Department of Nephrology, University Hospital, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen, Germany. Vincent.Brandenburg@post.rwth-aachen.de
authors.forename: Vincent M
authors.initials: VM
authors.lastname: Brandenburg
authors.forename: Dirk
authors.initials: D
authors.lastname: Politt
authors.forename: Markus
authors.initials: M
authors.lastname: Ketteler
authors.forename: Walter J
authors.initials: WJ
authors.lastname: Fassbender
authors.forename: Nicole
authors.initials: N
authors.lastname: Heussen
authors.forename: Ralf
authors.initials: R
authors.lastname: Westenfeld
authors.forename: Thomas
authors.initials: T
authors.lastname: Freuding
authors.forename: Juergen
authors.initials: J
authors.lastname: Floege
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Ittel
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D015519:Bone Density; D002117:Calcitriol / Q000097:blood; D003404:Creatinine / Q000097:blood; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016030:Kidney Transplantation; D008159:Lumbar Vertebrae / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D015675:Osteocalcin / Q000097:blood; D011184:Postoperative Period; D013997:Time Factors
chemical_list: D015675:Osteocalcin; D003404:Creatinine; D002117:Calcitriol