title: Marked diurnal variation in urinary excretion of pyridinium cross-links in premenopausal women.
abstract: To investigate whether bone resorption exhibits a diurnal variation in healthy premenopausal women, we measured urinary excretion of pyridinoline and deoxypyridinoline cross-links (U-Pyr/Cr and U-D-Pyr/Cr) every 3 h over a 24-h period in 12 healthy premenopausal women (mean +/- 1 SD age, 32 +/- 5 yr). To study diurnal variation, U-Pyr/Cr and U-D-Pyr/Cr are the best available markers of bone resorption for a diurnal variation study, as they are not influenced by diet. Plasma osteocalcin and serum alkaline phosphatase (markers of bone formation) were also measured. A marked diurnal rhythm was observed in U-Pyr/Cr and U-D-Pyr/Cr, with the peak between 0500-0800 h and the nadir between 1400-2300 h. The fluctuation was 2-fold over the 24-h period, with a mean fall of 25-35% between 0800-1100 h. This study demonstrates a marked diurnal variation in the new biochemical markers of bone resorption, U-Pyr/Cr and U-D-Pyr/Cr, in premenopausal women. Furthermore, this study emphasizes the importance of regulating the time of the urine sample taken for measuring urinary pyridinium cross-links for clinical investigations as well as in clinical practice.
authors.affiliation: Department of Clinical Chemistry, Glostrup Hospital, University of Copenhagen, Denmark.
authors.forename: A
authors.initials: A
authors.lastname: Schlemmer
authors.forename: C
authors.initials: C
authors.lastname: Hassager
authors.forename: S B
authors.initials: SB
authors.lastname: Jensen
authors.forename: C
authors.initials: C
authors.lastname: Christiansen
mesh_terms: D000328:Adult; D000596:Amino Acids / Q000652:urine*; D015415:Biomarkers / Q000652:urine; D001862:Bone Resorption / Q000652:urine; D002940:Circadian Rhythm; D003404:Creatinine / Q000652:urine; D005260:Female; D006801:Humans; D008593:Menopause; D012016:Reference Values; D012044:Regression Analysis
chemical_list: D000596:Amino Acids; D015415:Biomarkers; C015484:pyridinoline; C036020:deoxypyridinoline; D003404:Creatinine