25-Hydroxyvitamin D3 1-alpha-Hydroxylase25-Hydroxyvitamin D 2CalcifediolVitamin DVitamin D DeficiencyCholecalciferolHydroxycholecalciferolsErgocalciferolsDihydroxycholecalciferols24,25-Dihydroxyvitamin D 3Steroid HydroxylasesParathyroid HormoneCalcitriolSerumVitamin D-Binding ProteinRicketsSunlightCholestanetriol 26-MonooxygenaseReceptors, CalcitriolSeasonsDietary SupplementsVitaminsSerum AlbuminPhosphorusCalcium, DietaryBiological MarkersCalciumOsteomalaciaBone DensityCross-Sectional StudiesNutritional StatusHydroxylationRisk FactorsProspective StudiesBone and BonesKidneyCase-Control StudiesSkin PigmentationLinear ModelsChromatography, High Pressure LiquidCytochrome P-450 Enzyme SystemRadioimmunoassayDietBone Density Conservation AgentsSerum Albumin, BovineCohort StudiesFood, FortifiedPhosphatesEuropean Continental Ancestry GroupAlkaline PhosphatasePrevalenceHypoparathyroidismTime FactorsNutrition SurveysBody Mass IndexHypercalcemiaReference ValuesCholestenesDehydrocholesterolsNutritional RequirementsTandem Mass SpectrometryMass SpectrometryDouble-Blind MethodPregnancyAfrican AmericansChromatography, LiquidHypophosphatemia, FamilialAbsorptiometry, PhotonPostmenopauseOsteoporosisIntestinal AbsorptionImmunoassayMultivariate AnalysisBostonHyperparathyroidism, SecondaryUnited StatesOsteocalcinAdrenodoxinFractures, BoneNutrition PolicyFollow-Up StudiesLogistic ModelsMilkEnzyme-Linked Immunosorbent AssayHypocalcemiaSpectrophotometry, UltravioletNebraskaDose-Response Relationship, DrugOdds RatioRegression AnalysisAge FactorsChickensAdministration, OralHyperparathyroidismBone RemodelingParathyroid GlandsHyperparathyroidism, PrimaryRenal Insufficiency, ChronicMongoliaBone Resorption