title: A cross-sectional study on biochemical parameters of bone turnover and vitamin d metabolites in healthy dutch children and young adults.
abstract: OBJECTIVE
  To provide reference data of biochemical markers of bone turnover and vitamin D metabolites for children and young adults.
  
  
  METHODS
  Blood samples were taken from 176 healthy Dutch children and young adults (age range 7.6-25.3 years) to assess serum calcium, alkaline phosphatase, inorganic phosphate, osteocalcin, collagen type I cross-linked N-telopeptide, N-terminal propeptide of type I procollagen, 25-hydroxyvitamin D3, and 1,25-dihydroxyvitamin D3 levels. Cross-linked telopeptide of type I collagen and carboxy-terminal propeptide of type I procollagen were assessed in 286 subjects (age range 1.4-25.3 years).
  
  
  RESULTS
  Calcium and vitamin D levels were independent of age. The peak concentrations for collagen type I cross-linked N-telopeptide, cross-linked telopeptide of type I collagen, carboxy-terminal propeptide of type I procollagen, N-terminal propeptide of type I procollagen, alkaline phosphatase, and osteocalcin were found during puberty, in girls approximately 2.5 years earlier than in boys. Strong correlations were found between the markers of bone turnover, while no correlation was found between the markers of bone turnover and bone mineral density measured by dual-energy X-ray absorptiometry.
  
  
  CONCLUSIONS
  Single measurements of bone markers cannot predict bone density. Reference data according to gender, age, and Tanner stage are given which allow calculating standard deviation scores adjusted for age and gender.
authors.affiliation: Department of Pediatrics, Subdivision Endocrinology, Sophia Children's Hospital Rotterdam, The Netherlands. vandesluis@alkg.azr.nl
authors.forename: Inge M
authors.initials: IM
authors.lastname: van der Sluis
authors.forename: Wim C
authors.initials: WC
authors.lastname: Hop
authors.forename: Johannes P T M
authors.initials: JP
authors.lastname: van Leeuwen
authors.forename: Huib A P
authors.initials: HA
authors.lastname: Pols
authors.forename: Sabine M P F
authors.initials: SM
authors.lastname: de Muinck Keizer-Schrama
mesh_terms: D000293:Adolescent; D000328:Adult; D000469:Alkaline Phosphatase / Q000097:blood; D015415:Biomarkers / Q000097:blood*; D016723:Bone Remodeling; D002112:Calcifediol / Q000097:blood; D002117:Calcitriol / Q000097:blood; D002118:Calcium / Q000097:blood; D002648:Child; D003094:Collagen / Q000097:blood; D024042:Collagen Type I; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D009426:Netherlands; D015675:Osteocalcin / Q000097:blood; D010446:Peptide Fragments / Q000097:blood; D010455:Peptides / Q000097:blood; D010710:Phosphates / Q000097:blood; D011347:Procollagen / Q000097:blood; D012016:Reference Values; D014807:Vitamin D / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D024042:Collagen Type I; D010446:Peptide Fragments; D010455:Peptides; D010710:Phosphates; D011347:Procollagen; C052929:collagen type I trimeric cross-linked peptide; C047202:procollagen Type I N-terminal peptide; C042813:procollagen type I carboxy terminal peptide; D015675:Osteocalcin; D014807:Vitamin D; D003094:Collagen; D000469:Alkaline Phosphatase; D002117:Calcitriol; D002112:Calcifediol; D002118:Calcium