Diurnal, week-to-week, and long-term variation in urine deoxypyridinoline cross-link excretion in healthy older women.
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.
Allain
Theresa J
TJ
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
Abraha
Hagosa D
HD
Ouldred
Emma L
EL
Ajmal
Raheela
R
Buxton-Thomas
Muriel S
MS
Gray
Beverley C
BC
Dnm
Jackson
Stephen H D
SH
Blackburn
Ann M
AM
Moniz
Caje F
CF
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
D000596:Amino Acids; C036020:deoxypyridinoline