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
RJ Allison, A Farooq, A Cherif, B Hamilton… - British Journal of …, 2018 - bjsm.bmj.com
British Journal of Sports Medicine, 2018•bjsm.bmj.com
Background 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. Methods 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 …
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. Methods 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 …
Background
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.
Methods
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.
Results
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).
Conclusion
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.
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