title: Cortical bone status is associated with serum osteoprotegerin concentration in men: the STRAMBO study.
abstract: BACKGROUND
  Osteoprotegerin (OPG) is an inhibitor of bone resorption, but its relationship to bone microarchitecture remains unclear.
  
  
  OBJECTIVE
  Our objective was to study the relationship between OPG concentration and bone microarchitecture in men.
  
  
  METHODS
  We conducted a cross-sectional study of a population-based cohort of 1149 men aged 20-87 yr.
  
  
  METHODS
  We assessed bone microarchitecture at the distal radius and tibia by high-resolution peripheral quantitative computed tomography (XtremeCT Scanco) and measured serum OPG concentration and bone turnover markers: osteocalcin, bone-specific alkaline phosphatase, N-terminal extension type I collagen propeptide, C-terminal type 1 collagen telopeptide, and urinary deoxypyridinoline.
  
  
  METHODS
  Differences were assessed in bone microarchitectural parameters across the OPG quartiles in the models adjusted for age, weight, height, physical activity, ischemic heart disease, diabetes mellitus, calcium intake, serum levels of free testosterone, bioavailable 17β-estradiol, PTH, 25-hydroxycholecalciferol, and creatinine.
  
  
  RESULTS
  After adjustment for the confounders, men in the highest (fourth) quartile of OPG levels (>4.55 pmol/liter) had higher total cross-sectional area and trabecular area at the distal radius and distal tibia (3.3-6.0%, P < 0.05). At both skeletal sites, the highest OPG quartile was associated with lower cortical thickness (8.2%, P < 0.001, and 3.7%, P < 0.05) and volumetric bone mineral density (vBMD, 2.7%, P < 0.001, and 1.6%, P < 0.005) compared with the three lower quartiles combined. Associations of OPG level with trabecular vBMD, number, thickness, and distribution were not significant. Men in the fourth OPG quartile had higher levels of bone resorption markers (11.8-13.1%, P < 0.01-0.001).
  
  
  CONCLUSIONS
  Men with higher serum OPG concentration had lower cortical thickness and vBMD, probably due to accelerated endo- and intracortical bone turnover, but higher cross-sectional area possibly due to periosteal apposition.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche 1033, University of Lyon, Hospices Civils de Lyon, 69437 Lyon, France. pawel.szulc@inserm.fr
authors.forename: P
authors.initials: P
authors.lastname: Szulc
authors.forename: G
authors.initials: G
authors.lastname: Hawa
authors.forename: S
authors.initials: S
authors.lastname: Boutroy
authors.forename: N
authors.initials: N
authors.lastname: Vilayphiou
authors.forename: M
authors.initials: M
authors.lastname: Schoppet
authors.forename: R
authors.initials: R
authors.lastname: Chapurlat
authors.forename: L C
authors.initials: LC
authors.lastname: Hofbauer
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density / Q000502:physiology*; D001842:Bone and Bones / Q000502:physiology*; D003430:Cross-Sectional Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D053244:Osteoprotegerin / Q000097:blood*; D011446:Prospective Studies; D013739:Testosterone / Q000097:blood
chemical_list: D053244:Osteoprotegerin; D013739:Testosterone