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Br J Sports Med. 2018 Apr;52(8):522-526. doi: 10.1136/bjsports-2016-097130. Epub 2017 Aug 10.

Why don't serum vitamin D concentrations associate with BMD by DXA? A case of being 'bound' to the wrong assay? Implications for vitamin D screening.

Author information

Department of Exercise and Sport Science, ASPETAR, Orthopaedic and Sports Medicine Hospital, Doha, Qatar.
Research Institute for Sport and Exercise Science, Liverpool John Moores University, Auckland, UK.
Arsenal Football Club, London, UK.
Athlete Health and Performance Research Centre, ASPETAR, Orthopaedic and Sports Medicine Hospital, Doha, Qata.
Department of Sports Medicine, High Performance Sport New Zealand, Auckland, Australia.
Research Institute of Sport and Exercise Sciences, University of Canberra, Australia.



The association between bone mineral density (BMD) and serum25-hydroxyvitamin D (25(OH)D) concentration is weak, particularly in certain races (eg, BlackAfrican vs Caucasian) and in athletic populations. We aimed to examine if bioavailable vitamin D rather than serum 25(OH)D was related to markers of bone health within a racially diverse athletic population.


In 604 male athletes (Arab (n=327), Asian (n=48), Black (n=108), Caucasian (n=53) and Hispanic (n=68)), we measured total 25(OH)D, vitamin D-binding protein and BMD by DXA. Bioavailable vitamin D was calculated using the free hormone hypothesis.


From 604 athletes, 21.5% (n=130) demonstrated severe 25(OH)D deficiency, 37.1% (n=224) deficiency, 26% (n=157) insufficiency and 15.4% (n=93) sufficiency. Serum 25(OH)D concentrations were not associated with BMD at any site. After adjusting for age and race, bioavailable vitamin D was associated with BMD (spine, neck and hip). Mean serum vitamin D binding protein concentrations were not associated with 25(OH)D concentrations (p=0.392).


Regardless of age or race, bioavailable vitamin D and not serum 25(OH)D was associated with BMD in a racially diverse athletic population. If vitamin D screening is warranted, clinicians should use appropriate assays to calculate vitamin D binding protein and bioavailable vitamin D levels concentrations than serum 25(OH)D. In turn, prophylactic vitamin D supplementation to 'correct' insufficient athletes should not be based on serum 25(OH)D measures.


Athlete; Biochemistry; Bone Mineral Density

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