J Bone Miner Metab (2008) 26:86–92 DOI 10.1007/s00774-007-0791-7
© Springer 2008
ORIGINAL ARTICLE Farhad Hosseinpanah · Mehdi Rambod Arash Hossein-nejad · Bagher Larijani · Fereidoun Azizi
Association between vitamin D and bone mineral density in Iranian postmenopausal women
Received: March 10, 2007 / Accepted: July 13, 2007
Abstract The role of vitamin-D in determining bone mineral density (BMD), especially in less severe vitamin D deficiency, is still unclear. To investigate the possible association between 25-hydroxyvitamin D [25(OH)D] and BMD, 245 healthy free-living postmenopausal women, aged between 40 and 80, were randomly selected from participants of a population-based study. BMD was measured at the lumbar spine and hip by dual X-ray absorptiometry (Lunar DPXMD 7164). Serum 25(OH)D, parathyroid hormone (PTH), calcium, phosphorus, total and bone alkaline phosphatases, and urine deoxypyridinoline were measured. PTH was logarithmically transformed (LnPTH). Linear regression models were developed to determine the association between serum 25(OH)D and BMD at different sites. Means of age and duration of menopause were 57.7 ± 7 and 9.4 ± 6.8 years, respectively. Mean 25(OH)D was 73.0 ± 62.3 nmol/l; 5.3% (n = 13) had 25(OH)D < 25 nmol/l and 37.6% (n = 92) had 25(OH)D between 25 and 50 nmol/l. Eleven percent of the women (n = 27) were osteoporotic in femoral neck and 25.3% of them (n = 62) were osteoporotic in lumbar spine sites. 25(OH)D correlated inversely with LnPTH (r = −0.25, P < 0.01). In the multivariate analyses, no association was found between 25(OH)D and BMD at any of the skeletal sites after adjusting for age, duration of menopause, body mass index, calcium, and LnPTH. However, BMD was associated inversely with LnPTH only in femoral neck but not in the other sites. This study did not show any association between 25(OH)D and BMD in freeliving Iranian postmenopausal women. Key words vitamin D · bone mineral density · osteoporosis · parathyroid hormone (PTH) · postmenopausal women F. Hosseinpanah (*) · M. Rambod · F. Azizi Obesity Research Center, Research Institute for Endocrine Sciences, Shaheed Beheshti University of Medical Sciences, P.O. Box 193-4763, Tehran, Iran Tel. +98-21-2240-9309; Fax +98-21-2240-2463 e-mail:
[email protected] A. Hossein-nejad · B. Larijani Endocrine and Metabolism Research Center, Tehran University of Medical Sciences, Tehran, Iran
Introduction The role of vitamin D and its metabolites on bone health has been recognized for a long time [1]. Severe vitamin D deficiency causes overt osteomalacia in adults; mild to moderate vitamin D deficiency, also called vitamin D insufficiency, causes secondary hyperparathyroidism. Hence, vitamin D insufficiency might increase bone turnover and bone loss mainly from cortical sites [2], especially in postmenopausal women [3]. There is a rich ongoing debate about the association between 25-hydroxyvitamin D [25(OH)D] and bone mineral density (BMD). Some studies suggest that a low serum 25(OH)D is associated with low BMD [4–13], while others suggest no significant association between the two variables [14–17]. Certainly, these studies are very distinct from each other regarding population characteristics; only a few of the studies are population based [15,17,18]. In addition, the association between 25(OH)D and BMD was found only in particular subgroups such as in those with low vitamin D levels [4,6,13], in osteoporotic subjects [4,5,7,13], or in the elderly [8,9], or at particular sites [6]. Villareal et al. [4], for example, found a positive association between 25(OH)D and vertebral BMD in only a low level of 25(OH)D (
