title: Diurnal, week-to-week, and long-term variation in urine deoxypyridinoline cross-link excretion in healthy older women.
abstract: OBJECTIVE
  To establish a reference range for morning and afternoon excretion of urinary deoxypyridinoline (DPD) in apparently healthy older women selected from a volunteer database. To assess the extent of diurnal variation and short and long-term within-subject longitudinal variation.
  
  
  METHODS
  Prospective, observational, cohort study.
  
  
  METHODS
  Clinical Age Research Unit, King's College School of Medicine, London, United Kingdom.
  
  
  METHODS
  Forty-two women aged 68 to 89 (median age 75) selected from a volunteer database.
  
  
  METHODS
  Subjects completed an osteoporosis risk factor questionnaire and a physical examination and had a measurement of the broadband ultrasound attenuation and speed of sound of their right heel. Subjects provided six urine samples: morning and afternoon at baseline and 1 week and 60 weeks later for measurement of DPD.
  
  
  RESULTS
  The mean baseline values for DPD of morning and afternoon samples were 7.2 nM/mM and 6.0 nM/mM creatinine, respectively. The majority of subjects showed diurnal variation, with mean afternoon values 15% lower than morning values (P <.0001 for afternoon vs morning values). The mean difference in DPD after 60 weeks was 1.67 nM/mM for morning and 1.34 nM/mM for afternoon creatinine. This difference was not significant. Some individuals displayed marked changes in DPD excretion with no change in health status or treatment. DPD excretion in a nonfasting afternoon sample showed similar characteristics to morning void samples in terms of scatter, week-to-week variation, and long-term reproducibility.
  
  
  CONCLUSIONS
  The study was set up to provide background data to assist the development of a clinical osteoporosis service for older women. Further studies are needed to determine whether these measurements predict fracture risk and respond to treatment changes in this age group.
authors.affiliation: Clinical Age Research Unit and Department of Clinical Biochemistry, King's College School of Medicine and Dentistry, London, United Kingdom. theresa.allain@blueyonder.co.uk
authors.forename: Theresa J
authors.initials: TJ
authors.lastname: Allain
authors.forename: Hagosa D
authors.initials: HD
authors.lastname: Abraha
authors.forename: Emma L
authors.initials: EL
authors.lastname: Ouldred
authors.forename: Raheela
authors.initials: R
authors.lastname: Ajmal
authors.forename: Muriel S
authors.initials: MS
authors.lastname: Buxton-Thomas
authors.forename: Beverley C
authors.initials: BC
authors.lastname: Gray
authors.lastname: Dnm
authors.forename: Stephen H D
authors.initials: SH
authors.lastname: Jackson
authors.forename: Ann M
authors.initials: AM
authors.lastname: Blackburn
authors.forename: Caje F
authors.initials: CF
authors.lastname: Moniz
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000596:Amino Acids / Q000493:pharmacokinetics* / Q000652:urine*; D002940:Circadian Rhythm; D015331:Cohort Studies; D005260:Female; D006801:Humans; D010024:Osteoporosis / Q000652:urine*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012016:Reference Values; D012737:Sex Factors; D013997:Time Factors
chemical_list: D000596:Amino Acids; C036020:deoxypyridinoline