title: Low 25(OH) D serum levels are related with hip fracture in postmenopausal women: a matched case-control study.
abstract: OBJECTIVE
  There is limited information on the prevalence of vitamin D deficiency among patients diagnosed with hip fracture in the Chinese Han population. Therefore, the aim of this study was to assess the effects of change in the serum levels of 25-hydroxyvitamin D [25(OH) D] and intact parathyroid hormone (iPTH) among postmenopausal women in North China with confirmed hip fracture.
  
  
  METHODS
  This study was done from May 1, 2012 to April 30, 2014. Three hundred and forty-nine postmenopausal women who were diagnosed with first-ever hip fracture and 349 matched controls without fracture were used for this study. The 25(OH) D, iPTH, alkaline phosphatase, calcium, and phosphorus levels were measured in fasting venous blood samples collected from the subjects. A predesigned questionnaire was used to collect information on covariates for multivariate analyses to evaluate the hypothesized relationship between vitamin D deficiency and fracture risk.
  
  
  RESULTS
  The serum 25(OH) D levels were found to be significantly (P < 0.0001) lower in hip fracture patients than in the controls [37.0 (interquartile range [IQR] 28.0-48.0) nmol/L vs. 41.3 (IQR 32.0-54.5) nmol/L; P < 0.0001], and the iPTH levels were significantly higher in the former group [10.2 (IQR 6.3-14.9) pmol/L vs. 5.8 (IQR 4.1-6.6) pmol/L; P < 0.0001]. Further, a 25(OH) D level ≤50 nmol/L was found to independently indicate the occurrence of hip fracture [odds ratio (OR), 3.023; 95 % confidence interval (CI) 2.154-4.298], as well as hip fracture with concomitant upper limb fracture (OR 4.473; 95 % CI 2.984-10.532). Similarly, a serum iPTH level ≥6.8 pmol/L independently indicated the development of hip fracture (OR 2.498; 95 % CI 1.764-3.942), as well as hip fracture with concomitant upper limb fracture (OR 3.254; 95 % CI 1.998-7.984).
  
  
  CONCLUSIONS
  Vitamin D insufficiency and secondary hyperparathyroidism were found to be common problems in the sample of postmenopausal women who had experienced hip fracture. Monitoring the alterations in the serum levels of 25(OH) D and iPTH could be applied clinically as independent risk factors for hip fracture.
authors.affiliation: Institute of Traumatic Orthopedics, The 89th Hospital of People's Liberation Army, No. 256 Beigongxi Str, Weifang, 261021, Shandong Province, People's Republic of China. fxm70xe@126.com.
authors.forename: Xing-Mao
authors.initials: XM
authors.lastname: Fu
authors.affiliation: Institute of Traumatic Orthopedics, The 89th Hospital of People's Liberation Army, No. 256 Beigongxi Str, Weifang, 261021, Shandong Province, People's Republic of China. f-shg@163.com.
authors.forename: Shao-Guang
authors.initials: SG
authors.lastname: Fan
authors.affiliation: Institute of Traumatic Orthopedics, The 89th Hospital of People's Liberation Army, No. 256 Beigongxi Str, Weifang, 261021, Shandong Province, People's Republic of China. tangrenfeng88@163.com.
authors.forename: Shu-Liang
authors.initials: SL
authors.lastname: Li
authors.affiliation: Institute of Traumatic Orthopedics, The 89th Hospital of People's Liberation Army, No. 256 Beigongxi Str, Weifang, 261021, Shandong Province, People's Republic of China. myukizasd@163.com.
authors.forename: Yi-Sheng
authors.initials: YS
authors.lastname: Chen
authors.affiliation: Institute of Traumatic Orthopedics, The 89th Hospital of People's Liberation Army, No. 256 Beigongxi Str, Weifang, 261021, Shandong Province, People's Republic of China. lstelake34@sina.com.
authors.forename: Hai
authors.initials: H
authors.lastname: Wu
authors.affiliation: Institute of Traumatic Orthopedics, The 89th Hospital of People's Liberation Army, No. 256 Beigongxi Str, Weifang, 261021, Shandong Province, People's Republic of China. hongsemian32@126.com.
authors.forename: Yan-Long
authors.initials: YL
authors.lastname: Guo
mesh_terms: D016022:Case-Control Studies; D005260:Female; D006620:Hip Fractures / Q000097:blood*; D006801:Humans; D008875:Middle Aged; D017698:Postmenopause; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D