title: [Can sleep urine calcium concentration corrected by osmolality as a screening test identify subjects with risk to develop osteoporosis?].
abstract: The reliability of overnight (sleep) urine (SU) and 2nd morning urine (2MU) were compared with that of 24-hour urine (24 U) for the evaluation of bone resorption markers. A total of 50 women were subjected to the study was were divided into two groups according to their lumbar bone mineral density, namely 25 females with normal BMD (mean age 47) and 25 women with low BMD (mean age 78). Calcium (Ca), collagen degradation products crosslaps (CTx), pyridinoline (Pyr) and deoxypyridinoline (D-Pyr) were measured in 24 U, SU and 2MU and corrected for urine volume with creatinine (Cr) and osmolality(Osm). Among these four components, the corrected values tended to be higher in SU than 2MU, regardless of the method of correction and BMD level. Ca, CTx, Pyr and D-Pyr concentrations in spot urine were always significantly correlated with total excretion/body weight (Kg) regardless of the method of correction and BMD level. In low BMD subjects, Ca, CTx and D-Pyr concentrations corrected by Osm with further correction by body weight as an index of body size in the SU were significantly correlated with BMD. The SU may be a sensitive indicator of augmented nighttime bone resorption replacing 24 U especially on correction by Osm to eliminate the influence of sodium intake as an extraskeletal factor. In 51 women with normal BMD (A) with a mean age of 56, 16 with osteopenia (B) with a mean age of 64 and 35 with osteoporosis (C) with a mean age of 71, correlation coefficients were calculated between lumbar BMD and Ca/Osm, Ca/Osm/Kg, Ca/Cr and Ca/Cr/Kg in SU. Although no significant difference of mean urine Ca values were found between A and B groups, Ca values in C were significantly higher than that of A regardless of the correction method. The mean value of Ca/Osm/Kg in C was significantly higher than that of B. Ca/Osm/Kg showed a significant negative correlation with BMD in C. On examination of the correlation between % change of BMD in 23 women with a mean age of 59 and Ca concentration in SU corrected by urine volume and body weight, Ca/Osm was -0.427 (p = 0.0419), Ca/Osm/Kg -0.450 (p = 0.0313), Ca/Cr -0.400 (p = 0.058) and Ca/Cr/Kg -0.420 (p = 0.0462), suggesting the usefulness of Ca/Osm/Kg as an indicator of low BMD in screening.
authors.affiliation: Division of Laboratory and Research, National Sanatorium Hyogo Chuo Hospital.
authors.forename: S
authors.initials: S
authors.lastname: Ohgitani
authors.forename: Y
authors.initials: Y
authors.lastname: Fujii
authors.forename: T
authors.initials: T
authors.lastname: Fujita
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000652:urine; D015519:Bone Density; D001842:Bone and Bones / Q000378:metabolism; D002118:Calcium / Q000652:urine*; D005260:Female; D006801:Humans; D008875:Middle Aged; D009994:Osmolar Concentration; D010024:Osteoporosis / Q000175:diagnosis* / Q000209:etiology; D015663:Osteoporosis, Postmenopausal / Q000175:diagnosis / Q000209:etiology; D012306:Risk; D012890:Sleep / Q000502:physiology
chemical_list: D015415:Biomarkers; D002118:Calcium