title: Prevalence of vitamin D insufficiency in Swiss teenagers with appendicular fractures: a prospective study of 100 cases.
abstract: BACKGROUND
  The significance of subclinical vitamin D deficiency in the pathogenesis of fractures in children and adolescents currently remains unclear.
  
  
  OBJECTIVE
  We aimed to determine the prevalence of vitamin D insufficiency and its effect on bone mineral density (BMD) and bone mineral content (BMC) values in a collective of Swiss Caucasian children with a first episode of appendicular fracture.
  
  
  METHODS
  One hundred teenagers with a first episode of appendicular fracture [50 upper limb fractures (group 1) and 50 lower limb fractures (group 2)] and 50 healthy controls (group 3) were recruited into a cross-sectional study. The BMC and BMD values were measured by dual-energy X-ray absorptiometry, and serum 25 hydroxyvitamin D [25(OH)D] was assessed by electrochemiluminescence immunoassays.
  
  
  RESULTS
  From the 100 injured teenagers in the study, 12 % had deficient vitamin D levels (<20 ng/mL; <50 nmol/L) and 36 % had insufficient levels (≥20 <30 ng/mL; ≥50 <78 nmol/L), whereas 6 and 34 % of healthy controls were, respectively, vitamin D deficient and insufficient. There were no significant differences for serum 25(OH)D levels, L2-L4 BMD Z-score, and L2-L4 BMC Z-score variables (p = 0.216) between the three groups nor for the calcaneal BMD Z-score variables (p = 0.278) between healthy controls and lower limb fracture victims. Investigations on the influences of serum 25(OH)D on BMD and BMC showed no correlation between serum 25(OH)D and L2-L4 BMD Z-scores (r = -0.15; p = 0.135), whereas low but significant inverse correlations were, surprisingly, detected between serum 25(OH)D and calcaneal BMD Z-scores (r = -0.21; p = 0.034) and between serum 25(OH)D and L2-L4 BMC Z-scores (r = -0.22; p = 0.029).
  
  
  CONCLUSIONS
  A significant proportion of Swiss Caucasian teenagers were vitamin D insufficient, independent of limb fracture status, in our study. However, this study failed to show an influence of low vitamin D status on BMD and/or BMC of the lumbar spine and heel.
authors.affiliation: Pediatric Orthopedic Unit, Department of Child and Adolescent, University of Geneva Children's Hospitals and University of Geneva Faculty of Medicine, 6 Rue Willy-Donzé, 1211 Geneva 14, Switzerland.
authors.forename: Dimitri
authors.initials: D
authors.lastname: Ceroni
authors.forename: Rebecca
authors.initials: R
authors.lastname: Anderson de la Llana
authors.forename: Xavier
authors.initials: X
authors.lastname: Martin
authors.forename: Léopold
authors.initials: L
authors.lastname: Lamah
authors.forename: Geraldo
authors.initials: G
authors.lastname: De Coulon
authors.forename: Katia
authors.initials: K
authors.lastname: Turcot
authors.forename: Victor
authors.initials: V
authors.lastname: Dubois-Ferrière
keywords: BMC; BMD; Dual-energy X-ray absorptiometry; Fracture; Insufficiency; Teenagers; Vitamin D