{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,14]],"date-time":"2026-05-14T08:56:07Z","timestamp":1778748967112,"version":"3.51.4"},"reference-count":61,"publisher":"The Endocrine Society","issue":"2","license":[{"start":{"date-parts":[[2020,12,6]],"date-time":"2020-12-06T00:00:00Z","timestamp":1607212800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/academic.oup.com\/journals\/pages\/open_access\/funder_policies\/chorus\/standard_publication_model"}],"funder":[{"DOI":"10.13039\/100007688","name":"American University of Beirut","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100007688","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100004338","name":"Saint Joseph University","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100004338","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000061","name":"Fogarty International Center","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100000061","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000063","name":"Office of Dietary Supplements","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100000063","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000002","name":"National Institutes of Health","doi-asserted-by":"publisher","award":["D43 TW009118"],"award-info":[{"award-number":["D43 TW009118"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2021,1,23]]},"abstract":"<jats:title>Abstract<\/jats:title>\n               <jats:sec>\n                  <jats:title>Context<\/jats:title>\n                  <jats:p>Questions regarding the superiority of free and bioavailable 25-hydroxyvitamin D [25(OH)D] in predicting health outcomes remain unresolved.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Objective<\/jats:title>\n                  <jats:p>This study investigates the impact of vitamin D variables\u2014total, bioavailable, or free 25(OH)D\u2014on indices of bone and mineral metabolism, at baseline and in response to 2 vitamin D doses.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Design<\/jats:title>\n                  <jats:p>Our objectives are implemented as exploratory analyses on data collected in a 1-year, double-blind, randomized controlled trial completed in July 2014.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Setting<\/jats:title>\n                  <jats:p>Participants were recruited from 3 major hospitals in an ambulatory setting.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Participants<\/jats:title>\n                  <jats:p>Participants were &amp;gt;65 years of age, overweight, and had a baseline serum 25(OH)D between 10 and 30 ng\/mL. A total of 221 participants completed the study.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Intervention<\/jats:title>\n                  <jats:p>Subjects were randomized to receive calcium and oral vitamin D3 (600 IU\/day or 3750 IU\/day) supplementation.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Results<\/jats:title>\n                  <jats:p>Participants who received the higher vitamin D dose had levels that were 1.3- to 1.4-fold higher than those taking the lower dose, for all variables (P value\u2005&amp;lt;\u20050.001). Serum values of bioavailable and free 25(OH)D were associated with total 25(OH)D, with r values of 0.942 and 0.943, respectively (P value\u2005&amp;lt;\u20050.001). Parathyroid hormone (PTH) was negatively associated with all vitamin D variables, with correlation coefficients ranging from \u22120.22 to \u22120.25, while calcium and bone turnover markers (carboxy-terminal collagen crosslinks and osteocalcin) did not. Only total 25(OH)D had a positive relationship with % change bone mineral density (BMD) at the femoral neck at 12 months, while only free and bioavailable 25(OH) had a positive relationship with % change total body BMD at 12 months.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Conclusion<\/jats:title>\n                  <jats:p>Calculated free and bioavailable 25(OH)D do not appear to be superior to total 25(OH)D in predicting indices of bone health in an elderly population.<\/jats:p>\n               <\/jats:sec>","DOI":"10.1210\/clinem\/dgaa780","type":"journal-article","created":{"date-parts":[[2020,12,6]],"date-time":"2020-12-06T02:23:21Z","timestamp":1607221401000},"page":"e990-e1001","source":"Crossref","is-referenced-by-count":18,"title":["Total, Bioavailable, and Free 25(OH)D Relationship with Indices of Bone Health in Elderly: A Randomized Controlled Trial"],"prefix":"10.1210","volume":"106","author":[{"given":"Malak","family":"El Sabeh","sequence":"first","affiliation":[{"name":"Scholars in Health Research Program, Department of Internal Medicine, American University of Beirut, Beirut, Lebanon"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Paola","family":"Ghanem","sequence":"additional","affiliation":[{"name":"Scholars in Health Research Program, Department of Internal Medicine, American University of Beirut, Beirut, Lebanon"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Laila","family":"Al-Shaar","sequence":"additional","affiliation":[{"name":"Scholars in Health Research Program, Department of Internal Medicine, American University of Beirut, Beirut, Lebanon"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Maya","family":"Rahme","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, Division of Endocrinology, Calcium Metabolism and Osteoporosis Program, Beirut, Lebanon"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Rafic","family":"Baddoura","sequence":"additional","affiliation":[{"name":"Department of Rheumatology, Hotel Dieu de France, Beirut, Lebanon"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Georges","family":"Halaby","sequence":"additional","affiliation":[{"name":"Department of Endocrinology, Hotel Dieu de France, Beirut, Lebanon"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ravinder J","family":"Singh","sequence":"additional","affiliation":[{"name":"Division of Clinical Biochemistry and Immunology, Mayo Clinic, Rochester, Minnesota"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Dirk","family":"Vanderschueren","sequence":"additional","affiliation":[{"name":"Department of Chronic Diseases, Metabolism and Ageing (CHROMETA), Laboratory of Clinical and Experimental Endocrinology, KU Leuven, Herestraat, Leuven, Belgium"},{"name":"Department of Endocrinology, University Hospitals Leuven, Herestraat, Leuven, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6446-3763","authenticated-orcid":false,"given":"Roger","family":"Bouillon","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, Division of Endocrinology, Katholieke Universiteit Leuven, Leuven, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2076-5858","authenticated-orcid":false,"given":"Ghada","family":"El-Hajj Fuleihan","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, Division of Endocrinology, Calcium Metabolism and Osteoporosis Program, Beirut, Lebanon"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"80","published-online":{"date-parts":[[2020,12,6]]},"reference":[{"issue":"3","key":"2021122205230814700_CIT0001","doi-asserted-by":"crossref","first-page":"266","DOI":"10.1056\/NEJMra070553","article-title":"Vitamin D deficiency","volume":"357","author":"Holick","year":"2007","journal-title":"N Engl J Med."},{"issue":"1-2","key":"2021122205230814700_CIT0002","doi-asserted-by":"crossref","first-page":"297","DOI":"10.1016\/j.jsbmb.2010.02.021","article-title":"Worldwide status of vitamin D nutrition","volume":"121","author":"Lips","year":"2010","journal-title":"J Steroid Biochem Mol Biol."},{"issue":"3","key":"2021122205230814700_CIT0003","doi-asserted-by":"crossref","first-page":"319","DOI":"10.1016\/j.chembiol.2013.12.016","article-title":"Vitamin D metabolism, mechanism of action, and clinical applications","volume":"21","author":"Bikle","year":"2014","journal-title":"Chem 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