title: Seasonal differences in biochemical parameters of bone remodelling.
abstract: OBJECTIVE
  To compare bone remodelling parameters in late autumn and early spring in 20 post-menopausal women.
  
  
  METHODS
  The parameters measured were serum osteocalcin and its apparent degree of carboxylation (measured by hydroxyapatite binding), total and bone specific alkaline phosphatase and urinary bone resorption markers, (pyridinoline and deoxypyridinoline).
  
  
  RESULTS
  Serum osteocalcin concentrations were lower in autumn than in spring but the degree of carboxylation was similar. Total and bone specific alkaline phosphatase activities in serum were higher in autumn than in spring. These results support previous observations. However, notable and previously unreported changes in urinary bone resorption markers were observed. Pyridinoline concentrations were lower and deoxypyridinoline higher in autumn compared with spring. The ratio of pyridinoline:deoxypyridinoline was therefore very different between the seasons.
  
  
  CONCLUSIONS
  The results clearly demonstrate that seasonal changes in these variables of bone remodelling must be taken into consideration when designing, reporting or analysing studies of bone metabolism in vivo.
authors.affiliation: University Department of Medicine and Therapeutics, Medical School, Aberdeen.
authors.forename: A S
authors.initials: AS
authors.lastname: Douglas
authors.forename: M H
authors.initials: MH
authors.lastname: Miller
authors.forename: D M
authors.initials: DM
authors.lastname: Reid
authors.forename: J D
authors.initials: JD
authors.lastname: Hutchison
authors.forename: R W
authors.initials: RW
authors.lastname: Porter
authors.forename: S P
authors.initials: SP
authors.lastname: Robins
mesh_terms: D000368:Aged; D000469:Alkaline Phosphatase / Q000378:metabolism; D000596:Amino Acids / Q000652:urine; D016723:Bone Remodeling / Q000502:physiology*; D002118:Calcium / Q000652:urine; D005260:Female; D006801:Humans; D008875:Middle Aged; D015675:Osteocalcin / Q000097:blood; D015663:Osteoporosis, Postmenopausal / Q000378:metabolism / Q000503:physiopathology*; D012621:Seasons
chemical_list: D000596:Amino Acids; D015675:Osteocalcin; C015484:pyridinoline; C036020:deoxypyridinoline; D000469:Alkaline Phosphatase; D002118:Calcium