Osteoporos Int

PurposeThe osteocyte exerts important effects on bone remodeling but its rhythmicity and effect on the rhythms of other bone cells are not fully characterized. The purpose of this study was to determine if serum sclerostin displays rhythmicity over a 24-hour (h) interval, similar to that of other bone biomarkers.MethodsSerum sclerostin, FGF-23, CTX, and P1NP were measured every 2 hours over a 24-h interval on 10 healthy men aged 20-65 years. Maximum likelihood estimates of the parameters in a repeated measures model were used to determine if these biomarkers displayed a diurnal, sinusoidal rhythm.ResultsNo discernible 24-h rhythm was identified for sclerostin (p = 0.99) or P1NP (p = 0.65). CTX rhythmicity was confirmed (p < 0.001), peaking at 05:30 (range 01:30\u201307:30). FGF-23 levels were also rhythmic (p < 0.001) but time of peak was variable (range 02:30-11:30). The only significant association identified between these four bone biomarkers was for CTX and P1NP mean 24-h metabolite levels (r = 0.65, p = 0.04).ConclusionsSclerostin levels do not appear to be rhythmic in men. This suggests that in contrast to CTX, serum sclerostin could be measured at any time of day. The 24-h profiles of FGF-23 suggest that a component of osteocyte function is rhythmic but its timing is variable. Our results do not support the hypothesis that osteocytes direct the rhythmicity of other bone turnover markers (CTX), at least not via a sclerostin mediated mechanism.R01 HL125893/HL/NHLBI NIH HHS/United StatesMRF515/Medical Research Foundation of Oregon/UL1 TR000128/TR/NCATS NIH HHS/United StatesT32 DK007446/DK/NIDDK NIH HHS/United StatesT32 DK007674/DK/NIDDK NIH HHS/United StatesU01 AG042124/AG/NIA NIH HHS/United StatesU01 AG042145/AG/NIA NIH HHS/United StatesT32 DK007674/National Institute of Diabetes and Digestive and Kidney Diseases/K23 AR070275/AR/NIAMS NIH HHS/United StatesM01 RR002635/RR/NCRR NIH HHS/United StatesP30 DK036836/DK/NIDDK NIH HHS/United StatesUL1TR000128/National Center for Advancing Translational Sciences/U19 OH010154/OH/NIOSH CDC HHS/United StatesU01 AG042168/AG/NIA NIH HHS/United StatesU01 AG042140/AG/NIA NIH HHS/United StatesK23 AR070275/National Institute of Arthritis and Musculoskeletal and Skin Diseases/P01 AG009975/AG/NIA NIH HHS/United StatesUL1 RR025758/RR/NCRR NIH HHS/United StatesU01 AG027810/AG/NIA NIH HHS/United StatesT32 DK007446/National Institute of Diabetes and Digestive and Kidney Diseases/R01 HL107240/HL/NHLBI NIH HHS/United StatesP01 AG009975/National Institute on Aging/U01 AG042143/AG/NIA NIH HHS/United StatesU01 AG042139/AG/NIA NIH HHS/United StatesU01 AR066160/AR/NIAMS NIH HHS/United States2018-11-01T00:00:00Z28744601PMC5859541vault:2761