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Bone Abstracts (2013) 1 PP32 | DOI: 10.1530/boneabs.1.PP32

ECTS2013 Poster Presentations Bone biomechanics and quality (28 abstracts)

Vitamin D levels of >85 nmol/l in the presence of adequate dietary Ca minimise bone turnover and improve bone strength

Peter O’Loughlin 1, , Alice Lee 1 , Paul Anderson 1, , Roland Steck 4 , Mark Forwood 5 , Rebecca Sawyer 1 & Howard Morris 1,


1IMVS Pathology, Adelaide, South Australia, Australia; 2University of Adelaide, Adelaide, South Australia, Australia; 3University of South Australia, Adelaide, South Australia, Australia; 4Queensland University of Technology, Brisbane, Queensland, Australia; 5Griffith University, Gold Coast, Queensland, Australia.


We have reported femoral osteopenia in short term-vitamin D restricted rats without deterioration in tibial cortical bone volume (CBV), geometry or strength1. This study aimed to establish the effect of extended vitamin D deficiency in aged rat tibial volume and strength. Female Sprague-Dawley rats (9 m, n=6/group) were fed a diet containing varying vitamin D3 (D) levels (0, 2, 12, and 20 IU/day) with either low (0.1%, LCa) or high (1%, HCa) dietary calcium for 6 m. At 15 m blood was taken for 25 hydroxyvitamin D (25D) 1.25 dihydroxyvitamin D (1.25D), PTH and Ca analyses and tibiae and femora retrieved for bone analyses. 3D micro-CT scans (Skyscan 1174) were used to determine CBV, mid-shaft sagittal cortical thickness (Cth.sag) and metaphyseal BV/TV. Tibial peak load was determined by three-point bending (Test Resources 800LE4). 25D and 1.25D were determined by RIA (IDS) and PTH by IRMA (Immutopics). Group serum 25D levels ranged from 22 (±2.9) to 161 (±38.8) nmol/l and serum calcium levels from 2.5 (±0.05) to 3.2 (±0.2) mmol/l. Circulating 25D was a determinant of BV/TV (r2=0.23, P<0.001) and CBV (r2=0.22, P<0.01). In multiple linear regression neither serum Ca, PTH nor 1.25D were determinants of bone volume when 25D was accounted for. Dynamic histomorphometry indicated that high dietary Ca reduced bone turnover only in animals with circulating 25D levels above 85 nmol/l with the greatest reduction achieved in the 20 IU/day group (20D) (BFR (μm3/μm2 per day): LCa20D 33.9 (3.4) vs HCa20D 21.8 (2.3), P<0.05; Oc/BPm (n×10−3/mm): LCa20D 2.0 (0.2) vs HCa20D 1.1 (0.1), P<0.05). Tibial peak load was related to Cth.sag (r2=0.39, P<0.01). Thus, optimisation of bone volume and strength requires the combination of high dietary Ca intake and circulating 25D above 85 nmol/l. However, our previous demonstration that high dietary Ca is required to maximise circulating 25D levels2,3 in combination with the present findings suggest that the mechanism for vitamin D-optimisation of bone is not mediated via a calcaemic effect.

1. Lee AMC et al. JSBMB 121 284–287, 2010.

2. Anderson PH et al. JBMR 23 1789–97, 2008.

3. Anderson PH et al. JSBMB 121 288–921, 2010.

Volume 1

European Calcified Tissue Society Congress 2013

Lisbon, Portugal
18 May 2013 - 22 May 2013

European Calcified Tissue Society 

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