Abstract
PurposeThere 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.MethodsThis 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.ResultsThe 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).ConclusionsVitamin 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.
Highlights
Vitamin D deficiency is a common medical condition worldwide
Given this correlation between low vitamin D level and increased risk for hip fracture, Lips et al [13] reported that a daily vitamin D supplement of 800 IU in combination with calcium was an effective method to reduce the high incidence of nonvertebral fracture
Thirty-three cases diagnosed with hip fracture were excluded due to a major trauma or cancer affecting the bone, which contributed to the fractures; another 42 cases were excluded because of death or halfway transferring to other hospital
Summary
Vitamin D deficiency is a common medical condition worldwide. It usually develops because of insufficient sources of endogenous and exogenous vitamin D (inadequate intake or excessive consumption) and may eventually result in bone mass reduction, especially in elderly women [1]. A strong association between vitamin D deficiency and fracture development has been suggested, and thought to underlie the significant increases in mortality and morbidity rates of fracture patients [3, 4] Even survivors of this condition have been reported to be at high risk of permanent disability. Previous studies have suggested that lower levels of 25(OH) D could be regarded as a risk marker for hip fracture [11, 12]. Given this correlation between low vitamin D level and increased risk for hip fracture, Lips et al [13] reported that a daily vitamin D supplement of 800 IU in combination with calcium was an effective method to reduce the high incidence of nonvertebral fracture. The efficacy of vitamin D in preventing fractures could stem from its effects on muscle tissue (maintaining the normal structural and optimal functions of skeletal muscles), in addition to its known benefits in bone metabolism [14]
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