title: Pubertal timing and body mass index gain from birth to maturity in relation with femoral neck BMD and distal tibia microstructure in healthy female subjects.
abstract: Childhood body mass index (BMI) gain is linked to hip fracture risk in elderly. In healthy girls, menarcheal age is inversely related to BMI gain during childhood and to femoral neck areal bone mass density (aBMD) and distal tibia structural components at maturity. This study underscores the importance of pubertal timing in age-related fragility fracture risk.
  
  
  BACKGROUND
  Recent data point to a relationship between BMI change during childhood and hip fracture risk in later life. We hypothesized that BMI development is linked to variation in pubertal timing as assessed by menarcheal age (MENA) which in turn, is related to peak bone mass (PBM) and hip fracture risk in elderly.
  
  
  METHODS
  We studied in a 124 healthy female cohort the relationship between MENA and BMI from birth to maturity, and DXA-measured femoral neck (FN) aBMD at 20.4 year. At this age, we also measured bone strength related microstructure components of distal tibia by HR-pQCT.
  
  
  RESULTS
  At 20.4 ± 0.6 year, FN aBMD (mg/cm(2)), cortical thickness (μm), and trabecular density (mg HA/cm(3)) of distal tibia were inversely related to MENA (P = 0.023, 0.015, and 0.041, respectively) and positively to BMI changes from 1.0 to 12.4 years (P = 0.031, 0.089, 0.016, respectively). Significant inverse (P < 0.022 to <0.001) correlations (R = -0.21 to -0.42) were found between MENA and BMI from 7.9 to 20.4 years, but neither at birth nor at 1.0 year. Linear regression indicated that MENA Z-score was inversely related to BMI changes not only from 1.0 to 12.4 years (R = -0.35, P = 0.001), but also from 1.0 to 8.9 years, (R = -0.24, P = 0.017), i.e., before pubertal maturation.
  
  
  CONCLUSIONS
  BMI gain during childhood is associated with pubertal timing, which in turn, is correlated with several bone traits measured at PBM including FN aBMD, cortical thickness, and volumetric trabecular density of distal tibia. These data complement the reported relationship between childhood BMI gain and hip fracture risk in later life.
authors.affiliation: Division of Bone Diseases, Department of Rehabilitation and Geriatrics, Geneva University Hospitals and Faculty of Medicine, Rue Micheli-du-Crest 24, CH-1211, Geneva 14, Switzerland. Thierry.Chevalley@hcuge.ch
authors.forename: T
authors.initials: T
authors.lastname: Chevalley
authors.forename: J P
authors.initials: JP
authors.lastname: Bonjour
authors.forename: S
authors.initials: S
authors.lastname: Ferrari
authors.forename: R
authors.initials: R
authors.lastname: Rizzoli
mesh_terms: D015502:Absorptiometry, Photon; D000293:Adolescent; D001827:Body Height / Q000502:physiology*; D015992:Body Mass Index; D015519:Bone Density / Q000502:physiology*; D002648:Child; D005260:Female; D005272:Femur Neck / Q000000981:diagnostic imaging / Q000502:physiology*; D006801:Humans; D008572:Menarche; D011446:Prospective Studies; D013977:Tibia / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods; D055815:Young Adult