ePrints

Assessment of vitamin D status in male osteoporosis

Lookup NU author(s): Dr Ziad Al-Oanzi, Dr Stephen Tuck, Dr David Cook, Emeritus Professor Roger Francis, Dr Harish Datta

Downloads

Full text for this publication is not currently held within this repository. Alternative links are provided below where available.

Abstract

Background: Clinical assessment of vitamin D status often relies on measuring total circulating 25-hydroxy-vitamin D3 (25OHD 3), but much of each vitamin D metabolite is bound to plasma vitamin D-binding protein (DBP), such that the percentage of free vitamin is very low. We hypothesized that measurement of free rather than total 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] and 25OHD3 may provide better assessment of vitamin D status. We therefore aimed to assess vitamin D status in men with idiopathic osteoporosis, in whom possible secondary causes of osteoporosis had been excluded, and to determine the extent of change in biologically active "free" vitamin D caused by variation in plasma DBF concentrations. Methods: We measured 1,25(OH)2D3 and 25OHD3 in plasma samples from 56 men with idiopathic osteoporosis [mean (SD) age, 59.6 (13.6) years; range, 21-86 years] and 114 male controls [62.4 (10.4) years; range, 44-82 years]. Results: Mean total plasma 25OHD 3 in the 56 men with osteoporosis and the 114 controls was 44.7 (21) and 43.3 (17) nmol/L, respectively; total plasma 1,25(OH)2D 3 measured in randomly selected men with osteoporosis (n = 50) and controls (n = 50) was 90 (37) and 103 (39) pmol/L, respectively. Mean plasma DBF was significantly higher (P < 0.001) in men with osteoporosis [224 (62) mg/L; n = 56] than in the controls [143 (34) mg/L; n = 114], but calculated free plasma 25OHD3 and 1,25(OH)2D3 were significantly lower in the osteoporotic men than in controls [6.1 (3.1) vs 9.1 (4.4) pmol/L (P <0.00001) and 77 (37) vs 142 (58) fmol/L (P <0.00001), respectively]. Conclusions: Measurement of total vitamin D metabolites alone, although providing a crude assessment of vitamin D status, may not give an accurate indication of the free (biologically active) form of the vitamin. The ratio of total 25OHD3 and 1,25(OH)2D3 to plasma DBF, rather than total circulating vitamin D metabolites, may provide a more useful index of biological activity. Further studies are required to substantiate this hypothesis. © 2006 American Association for Clinical Chemistry.

Publication metadata

Author(s): Al-Oanzi ZH, Tuck SP, Raj N, Harrop JS, Summers GD, Cook DB, Francis RM, Datta HK

Publication type: Article

Publication status: Published

Journal: Clinical Chemistry

Year: 2006

Volume: 52

Issue: 2

Pages: 248-254

ISSN (print): 0009-9147

ISSN (electronic): 1530-8561

Publisher: American Association for Clinical Chemistry, Inc.

URL: http://dx.doi.org/10.1373/clinchem.2005.059568

DOI: 10.1373/clinchem.2005.059568

PubMed id: 16339300

Altmetrics

Share