中国北方地区老年人冬季维生素D缺乏与骨量丢失

背景：中国北方地区老年人维生素D营养状态存在季节变化,冬春季维生素D缺乏严重。目的：分析沈阳市老年人冬季维生素D缺乏对骨量丢失的影响。方法：随机选择沈阳市60岁以上汉族健康老年人100名,于2000-03检测受试者血浆中25羟维生素D、甲状旁腺激素、钙和磷,清晨空腹2h尿中脱氧吡啶、钙、磷、肌酐,2000-03/2005-03两次检测髋部骨密度。结果与结论：基线时,血浆25羟维生素D浓度为（31.0±12.30）nmol/L,40%受试者低于25nmol/L;血浆甲状旁腺激素水平为（29.4±11.5）ng/L,血浆25羟维生素D浓度低于25nmol/L者甲状旁腺激素水平为（34.6±13.5）ng/L,血浆25羟维生素D浓度与甲状旁腺激素呈负相关（r=-0.479,P〈0.0001）。5年后股骨颈骨丢失率为（3.05±4.07）%,大转子为（1.46±5.02）%,经体质量和身高变化率校正后,股骨颈骨丢失率与基线血浆25羟维生素D浓度呈负相关（r=-2.3,P=0.02）,股骨颈骨丢失率基线血浆25羟维生素D浓度≤25nmol/L者高于浓度〉25nmol/L者103%（F=7.2062,P=0.0085）。其他检测指标与骨丢失无显著相关性。说明老年人群冬季维生素D缺乏严重,维生素D缺乏促进骨量丢失,影响骨健康。     

汉族与维吾尔族50岁以上人群血清25羟维生素D_3水平差异及其与骨质疏松症关系

目的分析新疆乌鲁木齐地区汉族与维吾尔族50岁以上人群血清25羟维生素D3水平差异,探讨其与骨质疏松症的关系。方法年龄50岁以上并完成血清骨转化指标及骨密度测定患者1 223例,汉族882例,维吾尔族341例。分析2个民族年龄、骨密度、血清25羟维生素D3及血清钙、磷水平的差异。结果汉族和维吾尔族原发性骨质疏松检出率比较差异无统计学意义(P>0.05);2个民族血清钙、磷水平在有无骨质疏松上差异无统计学意义(P>0.05);骨密度正常者,维吾尔族25羟维生素D3水平(30.19±19.67)nmol/L较汉族(48.50±27.97)nmol/L低(P<0.01);骨质疏松者,维吾尔族血清25羟维生素D3水平(31.82±20.79)nmol/L较汉族(47.41±26.56)nmol/L低(P<0.01);年龄与血清25羟维生素D3水平无相关性(r=0.007,P=0.817)。结论不同民族间血清25羟维生素D3水平有差异,其差异与骨质疏松无关。     

汉族与维吾尔族50岁以上人群血清25羟维生素D3水平差异及其与骨质疏松症关系

目的分析新疆乌鲁木齐地区汉族与维吾尔族50岁以上人群血清25羟维生素D3水平差异,探讨其与骨质疏松症的关系。方法年龄50岁以上并完成血清骨转化指标及骨密度测定患者1 223例,汉族882例,维吾尔族341例。分析2个民族年龄、骨密度、血清25羟维生素D3及血清钙、磷水平的差异。结果汉族和维吾尔族原发性骨质疏松检出率比较差异无统计学意义(P>0.05);2个民族血清钙、磷水平在有无骨质疏松上差异无统计学意义(P>0.05);骨密度正常者,维吾尔族25羟维生素D3水平(30.19±19.67)nmol/L较汉族(48.50±27.97)nmol/L低(P<0.01);骨质疏松者,维吾尔族血清25羟维生素D3水平(31.82±20.79)nmol/L较汉族(47.41±26.56)nmol/L低(P<0.01);年龄与血清25羟维生素D3水平无相关性(r=0.007,P=0.817)。结论不同民族间血清25羟维生素D3水平有差异,其差异与骨质疏松无关。     

孕妇血清25羟维生素D与妊娠期高血压的相关性研究

目的:研究孕妇血清25羟维生素D与妊娠期高血压之间的相关性。方法:采用酶联免疫分析法检测妊娠期高血压患者及正常孕妇在不同孕周的25羟维生素D水平,分析其与妊娠期高血压之间的相关性。结果:在妊娠16~21周和28~33周时,对照组25羟维生素D水平分别为(38.90±6.07)nmol/L和(49.00±12.92)nmol/L;A组为(37.80±6.63)nmol/L和(48.00±12.84)nmol/L;B组为(29.60±6.98)nmol/L和(34.80±7.76)nmol/L;C组为(23.90±3.89)nmol/L和(28.40±4.46)nmol/L。孕晚期的25羟维生素D水平较孕中期升高。A组、B组、C组在不同孕周的25羟维生素D水平为依次递减。B组、C组分别与对照组相比,孕妇血清25羟维生素D水平均显著降低,而A组与对照组相比,无明显差异(P>0.05)。结论:孕妇血清25羟维生素D水平与妊娠期高血压严重程度呈负相关。孕妇25羟维生素D水平的下降早于子痫前期临床症状的出现,可协助预测子痫前期的发生。     

2型糖尿病患者血25羟维生素D的改变及其对糖代谢与骨密度的影响

目的 探讨2型糖尿病患者血25羟维生素D[25(OH)D]的改变及其对糖代谢与骨密度的影响.方法 选择我院住院的2型糖尿病患者258例,以25(OH)D为50 nmol/L为临界值进行分组,分为维生素D缺乏组[25 (OH)D＜50 nmol/L] 192例及维生素D相对不足组[25 (OH)D为50 ～ 70nmol/L]66例.双能X线骨密度仪(DXA)测量患者腰椎L2～L4及股骨颈骨密度,取腰椎Total值、股骨颈Neck和Total值为判定指标,采用稳态模型评估胰岛素抵抗(HOMA-IR)程度,收集分析患者糖代谢与骨代谢相关指标数据并进行统计分析.结果 258例2型糖尿病患者中骨质疏松57例,占22.1％.其中维生素D缺乏组与维生素D相对不足组的糖尿病病程、空腹胰岛素和胰岛素抵抗指数差异均有统计学意义[(7.98±1.09)、(3.77±1.21)年,(6.42±1.30)、(5.79±1.08) mU/L、(2.35±0.54)、(1.85±0.41),t值分别为4.849、3.871、2.705,P均＜0.05],而空腹血糖与糖化血红蛋白差异均无统计学意义(P均＞0.05),维生素D缺乏组与维生素D相对不足组的甲状旁腺激素、腰椎Total值、股骨颈Neck值、股骨颈Total值差异均有统计学意义[(36.51±7.59)、(32.02±6.89) ng/L,(0.87±0.14)、(0.99±0.12) g/cm2,(0.70±0.10)、(0.79±0.11)g/cm2,(0.84±0.14)、(0.97±0.15) g/cm2,t值分别为2.008、2.799、2.564、2.340,P均＜0.05].结论 2型糖尿病患者中普遍存在维生素D缺乏,维生素D的水平将影响糖尿病患者胰岛素抵抗和血糖控制及骨密度水平,导致骨质疏松发病率明显增加.因此,对糖尿病患者应进行常规维生素D检测,并对维生素D缺乏的患者及时给予维生素D补充治疗.     

25-羟维生素D水平与早期类风湿性关节炎的相关性研究

目的探讨25-羟维生素D浓度与早期类风湿性关节炎的相关性。方法收集东阳市人民医院2009年1～7月类风湿性关节炎患者126例,记录肿胀关节数、压痛关节数、骨侵蚀度等临床指标,并测定25-羟维生素D浓度,分析维生素D水平与患者临床指标的变化,并测定健康对照组40例25-羟维生素D浓度。结果类风湿性关节炎患者25-羟维生素D浓度为(21.3±4.8)ng/mL,健康对照者25-羟维生素D浓度为(37.2±8.6)ng/mL,类风湿性关节炎患者25-羟维生素D浓度低于健康对照者,差异有统计学意义(P0.05),25-羟维生素D浓度与类风湿性关节炎疾病严重程度密切相关,差异有统计学意义(P0.05)。结论外周血25-羟维生素D水平与类风湿性关节炎密切相关,但其作用机制有待深入研究。     

基于UPLC-MS/MS 建立早产儿血清25-(OH)D3 和3-epi-25-(OH)D3 检测新方法及临床初步应用

目的 建立血清25- 羟维生素D3[25-hydroxyvitamin D3, 25-(OH)D3] 及3-epi-25- 羟维生素D3[3-epi-25-hydroxyvitaminD3, 3-epi-25-(OH)D3] 超高效液相色谱- 串联质谱检测新方法（ultra-performance liquid chromatography-tandem massspectrometry,UPLC-MS/MS）,并在早产儿中开展初步应用。方法 采用液- 液萃取法提取化合物,五氟苯基丙基（pentafluorophenylpropyl,PFPP）色谱柱分离25-(OH)D3 与3-epi-25-(OH)D3;从最低定量限、线性关系、精密度与准确度等四个方面对新建方法进行验证,并对134 例早产儿血清样本进行检测分析。结果 25-(OH)D3 及3-epi-25-(OH)D3 的最低定量限分别为6.05±0.78 nmol/L,1.48±0.20 nmol/L;线性范围3.78 ～ 480.00 nmol/L,1.00 ～ 128.00 nmol/L;相关系数r2 为0.992 2,0.992 8;25-(OH)D3 与3-epi-25-(OH)D3 低、中、高浓度质控品的日内精密度和日间精密度均小于15.00%;回收率109.92%,102.25%,98.76%;97.75%, 95.25%,99.80%。134 例早产儿血清25-(OH)D3 平均浓度22.35±13.28nmol/L,3-epi-25-(OH)D3 平均浓度5.43±4.35 nmol/L;3-epi-25-(OH)D3 占总25-(OH)D3 的平均比例为19.96%±12.08%,范围0.00% ～ 60.62%。以25-(OH)D3 计算,维生素D（Vitamin D, Vit D）缺乏率、不足率、充足率分别为78.36%,19.40%,2.24%;以总25-(OH)D3 计算,Vit D 缺乏率、不足率、充足率分别为65.67%,26.12%,8.21%;二者Vit D 缺乏率及充足率的比较, 差异均有统计学意义（χ2=5.351,1.719,4.823,均P ＜ 0.05）。结论 本研究建立的UPLC-MS/MS检测法性能良好且能精准检测早产儿血清25-(OH)D3 浓度,在早产儿Vit D 评估方面具有较好的应用价值。     

血清25-羟维生素D水平与成人肥胖哮喘的相关性研究

目的探讨成人肥胖哮喘患者血清25-羟维生素D[25-hydroxyvitamin D,25(OH)D]水平,及其与γ-干扰素(interferon-γ,IFN-γ)、白介素-4(interleukin-4,IL-4)、IFN-γ/IL-4的相关性。方法入组2019年1~8月青岛大学附属青岛市市立医院支气管哮喘急性发作期患者及同期健康查体者,根据体重指数不同将其分为肥胖哮喘组21例、肥胖组19例、哮喘组21例、正常对照组21例,采用酶联免疫吸附测定法检测血清中25(OH)D、IFN-γ、IL-4浓度。比较各组25(OH)D、IFN-γ、IL-4水平的差异,采用Pearson相关性分析25(OH)D与IFN-γ、IL-4、IFN-γ/IL-4的相关性。结果肥胖哮喘组25(OH)D水平为(37.80±11.63)nmol/L,哮喘组为(45.40±10.58)nmol/L,肥胖组为(63.77±13.62)nmol/L,正常对照组为(82.17±9.83)nmol/L,肥胖哮喘组25(OH)D水平最低(P<0.05)。肥胖哮喘组血清25(OH)D水平与IFN-γ呈负相关(R=-0.445,P<0.05),与IL-4呈正相关(R=0.673,P<0.05),与IFN-γ/IL-4呈负相关(R=-0.654,P<0.05)。结论成人肥胖哮喘患者存在维生素D水平不足或缺乏,维生素D可能通过调节Th细胞分化方向参与肥胖哮喘的发病。     

血清25-羟维生素D浓度与2型糖尿病并发冠心病的关系

目的探讨2型糖尿病(T2DM)患者血清25-羟维生素D3[25(OH)D3]水平与冠心病发病率的相关性,及阿法骨化醇治疗是否降低T2DM患者新发冠心病的发病率。方法选取本院门诊及住院的T2DM患者280例,纳入研究前未合并冠心病,用酶联免疫吸附测定(ELISA)法测定患者血清25(OH)D3的浓度,根据血清25(OH)D3浓度分为低浓度组(T组,<45nmol/L,198例),高浓度组(C组,≥45nmol/L,82例),其中T组患者根据是否接受维生素D治疗分为两亚组(T1组:阿法骨化醇治疗;T2组:不接受维生素D治疗)。随访5年,测定患者初始及5年后血清低密度脂蛋白胆固醇(LDL-C)、糖化血红蛋白C(HbA1c)、超敏C反应蛋白(hsCRP)、25(OH)D3、甲状旁腺素(iPTH)等指标,分析血清25(OH)D3浓度与冠心病的发病相关关系,并计算随访期间累计冠心病发病率。另外选取体检中心健康志愿者30例作为健康对照组(N)组,测定以上指标。结果在T2DM患者中,血清25(OH)D3明显低于N组,C组、T1组、T2组与N组分别为(52.8±7.1)nmol/L、(34.7±8.4)nmol/L、(35.1±9.6)nmol/L vs(72.3±15.5)nmol/L(P<0.01),T1组患者经维生素D治疗后,血清25(OH)D3水平明显升高(34.7±8.4)nmol/L vs(55.7±10.6)nmol/L(P<0.05)。与T1组相比,T2组糖尿病5年新发冠心病发病率明显升高(39.4%vs 13.1%,P<0.05),与T2组相比,T1组给予阿法骨化醇治疗新发冠心病发病率明显降低(13.1%vs 39.4%,P<0.05)。结论 T2DM患者血清25(OH)D3低水平是并发冠心病的独立危险因素,活性维生素D治疗可以降低T2DM患者新发冠心病发病率。     

老年男性2型糖尿病患者甲状旁腺素、维生素D与骨密度的关系

目的 探讨老年男性2型糖尿病患者主要钙调激素甲状旁腺素(PTH)和维生素D的变化对骨密度的影响.方法 应用双能X线骨密度仪测定60例老年男性2型糖尿病患者的腰椎和髋部骨密度,检测血清中骨代谢及血糖相关的指标,并根据骨密度测定结果将60例老年男性2型糖尿病患者分为骨量减少组(32例)、骨质疏松组(12例)、正常组(16例),测定3组的血清PTH和25羟维生素D3,分析其与患者不同部位骨密度的相关性.结果 依据患者腰椎或髋部的骨密度值,骨质疏松的检出率为20.0％(12/60),骨量减少的检出率为53.3％(32/60).3组的血清PTH比较差异有统计学意义(F=3.32,P=0.043),骨量减少组、骨质疏松组与正常组相比,PTH水平明显上升[(44.87±10.62)、(50.24±20.32)μg/L与(36.96±12.36)μg/L,P均＜0.05].但25羟维生素D3浓度3组比较差异无统计学意义(P＞0.05).相关分析显示,PTH水平与髋部骨矿面密度(BMD)呈显著负相关(r=-0.224,P ＜0.05),与腰椎BMD无显著相关性(r=-0.187,P＞0.05).结论 老年男性2型糖尿病患者的髋部BMD与血清PTH浓度负相关.     

Vitamin D in older patients with cancer

Vitamin D insufficiency has been found to be as high as 75% among community-dwelling adults aged 65 and older. The purpose of this article is to provide a review of published literature focused on the benefits of vitamin D and calcium supplementation in older patients with cancer. Insufficient vitamin D levels may have considerable effects on cancer-related diagnosis and treatment. Patient education should include information concerning vitamin D and calcium administration to reduce falls and injury from falls and enhance functional status. This article will consider the issue of vitamin D levels related to cancer prevention, diagnosis, treatment, functional status, and falls in older patients with cancer. Dosing and serum measurement information will be discussed.     

10696例60岁以上老年人群血清25-羟基维生素D水平调查

目的研究中国部分地区60岁以上老年人群血清25-羟基维生素D(25OHD)水平,了解年龄、性别、季节和地区对维生素D分布的影响。方法选取来自不同经纬度的广州、上海、北京、长春和兰州的社区体检老年人群(60岁以上)共计10696例,采用高效液相色谱-串联质谱法检测血清25-羟基维生素D 2(25OHD 2)、25-羟基维生素D 3(25OHD 3),二者之和即为25OHD水平,按照年龄、性别、季节和地区分别进行分组分析。结果10696例60岁以上老年人群血清25OHD水平为(18.84±7.48)ng/mL,维生素D缺乏者59.99%,不足者32.28%,充足者仅7.72%,过量者无。维生素D缺乏率随年龄增长逐渐增加,80岁以上老人组高达68.33%,组间差异有统计学意义(χ2=30.404,P<0.05);不同性别维生素D营养状况比较,组间差异有统计学意义(χ2=13.472,P<0.05);不同季节比较,夏季缺乏率最低,为35.51%,组间差异有统计学意义(χ2=640.666,P<0.05);不同地区比较,广州地区缺乏率最低,为16.63%,组间差异有统计学意义(χ2=1808.145,P<0.05)。同地区不同年龄、性别、季节组维生素D营养情况比较,发现广州地区夏季缺乏率最低,为6.67%,兰州冬季缺乏率最高,达84.57%。结论60岁以上老年人群总体25OHD水平普遍偏低,维生素D水平处于严重缺乏状态,季节和纬度对维生素D的分布影响较大。     

Size at birth, adult intestinal calcium absorption and 1,25(OH)(2) vitamin D

BACKGROUND: Adult bone mineral status is modified by early environmental influences, but the mechanism of this phenomenon is unknown. Intestinal calcium absorption and vitamin D metabolism are integrally involved in bone metabolism and may be programmed during early life. AIM: To examine the early-life influences on calcium absorption and its control in 322 post-menopausal female twins. METHODS: Intestinal calcium absorption was assessed by the stable strontium (Sr) method. Serum PTH, 25(OH) and 1,25(OH)(2) vitamin D were measured and recalled birth weight recorded. RESULTS: Fractional intestinal Sr absorption (alpha Sr) was correlated with serum 1,25(OH)(2) vitamin D (p<0.001), but not with 25(OH) vitamin D. Birth weight was inversely associated with serum 1,25(OH)(2) vitamin D (p=0.04), the association being independent of serum calcium, phosphate, creatinine and PTH. Birth weight was inversely correlated with alpha Sr (p=0.03), this association being independent of age, season, customary calcium intake and serum 25(OH) vitamin D; however, when serum 1,25(OH)(2) vitamin D was added into the model, the association became non-significant, suggesting that the association was partially mediated via serum 1,25(OH)(2) vitamin D. DISCUSSION: We found a significant inverse association between birth weight and intestinal calcium absorption that is partially explained by an association between serum 1,25(OH)(2) vitamin D and birth weight. This suggests a mechanism whereby the intra-uterine environment might affect adult skeletal status.     

Assessment of vitamin D and calcium status in healthy adult Austrians

BACKGROUND: Because there is reason to assume that also in Austria calcium and vitamin D malnutrition is wide-spread, we initiated a comprehensive study on calcium and vitamin D status in relation to bone health in a large group of the normal adult population. SUBJECTS AND METHODS: We assessed dietary calcium and vitamin D intake, serum concentrations of Ca2+, phosphate, alkaline phosphatase, 25(OH)D, 1,25(OH)2D, parathyroid hormone (PTH), follicle-stimulating hormone (FSH), sex hormones and bone mineral density (BMD) by double-energy X-ray absorptiometry at five different skeletal sites in 648 females and 400 males (age 21-76 years). RESULTS: Mean daily intake of vitamin D (101 IU, range 0.2-320) and calcium (569 mg, range 40-2170) was significantly less than the respective recommended dietary allowances. Two hundred and seventy-one (26%) individuals had hypovitaminosis D with serum 25(OH)D < 12 ng mL(-1), while serum Ca2+ was less than normal in 82 (7.8%) subjects. Multiple regression analysis revealed significant correlations between mean calcium intake and BMD in the femoral region in the men (r = 0.13, P < 0.05) though not in the women. No consistent data could be obtained for associations between BMD and vitamin D status, except for 25(OH)D and BMD at the spine in the men (r = 0.10, P < 0.05). 25(OH)D correlated negatively (P < 0.05) with age in the women (r = -0.11) and with PTH in the women (r = -0.11) and men (r = -0.16). Inversely, a significant (P < 0.001) age-related increase in PTH was observed in both sexes (men, r = 0.19; women, r = 0.14). CONCLUSIONS: Prevalence of hypovitaminosis D in adult Austrians is an imminent risk for development of secondary hyperparathyroidism with advancing age, and requires timely correction of nutritional deficits.     

Underutilization of calcium and vitamin D by older adults in a large general internal medicine practice

The underutilization of calcium and vitamin D supplements in the prevention and treatment of osteoporosis is common among high-risk elders. Less is known about the prevalence and adequacy of calcium and vitamin D use by the general population of older adults. We performed a retrospective chart analysis of 617 women and 383 men over the age of 60 (mean age 73 +/- 9 years) seen at an internal medicine practice to establish the prevalence and evaluate the adequacy of calcium and vitamin D supplementation. Adequate supplementation was defined according to the National Osteoporosis Foundation guidelines and the National Institutes of Health Consensus Development Panel on Osteoporosis. Osteoporosis or osteopenia was documented in 207 (33.6%) women and 21 (5.5%) men (P < 0.01). Of 383 men, 116 (30.3%) used calcium, 25 (6.5%) used adequate doses of calcium, 109 (28.5%) used vitamin D, and only 8 (2.1%) used adequate doses of vitamin D. Of 617 women, 415 (67.3%) used calcium, 199 (32.3%) used adequate doses of calcium, 347 (56.2%) used vitamin D, and 83 (21.7%) used adequate doses of vitamin D. When compared with women, men were less likely to be on calcium (OR 0.21, 95% CI 0.16-0.28), on adequate calcium replacement (OR0.15, 95% CI 0.11-0.23), on vitamin D (OR 0.32, 95% CI 0.25-0.42), and on adequate vitamin D replacement (OR 0.13, 95% CI 0.07-0.26). Calcium and vitamin D were greatly underutilized among older patients in an internal medicine clinic. Inadequate replacement doses were common, and men were particularly susceptible to undertreatment.     

Measured free 25-hydroxyvitamin D in healthy children and relationship to total 25-hydroxyvitamin D,calculated free 25-hydroxyvitamin D and vitamin D binding protein

Backgroundvitamin D deficiency in children is still a global health problem. Measuring free 25-hydroxyvitamin D concentrations could provide a better estimate of the vitamin D status than total 25-hydroxyvitamin D (25(OH)D) levels.ObjectiveTo assess the relationship between measured free vitamin D (m-f25(OH)D) and calculated free 25(OH)D (c-f25(OH)D), total 25(OH)D, intact parathyroid hormone (iPTH) and other markers of phosphocalcic metabolism.To establish serum m-f25(OH)D concentrations corresponding to a total 25(OH)D > 50 nmol/L which is accepted as vitamin D-sufficiency status in children.DesignProspective cohort study.SettingJanuary and February 2017 in a Mediterranean population.Patientshealthy children.Measurementsm-f25(OH)D and vitamin D binding protein (VDBP) by ELISA. Free 25(OH)D was calculated using the formula described by Bikle.Resultsm-f25(OH)D directly correlated with total 25(OH)D (r:0.804,p < .001), serum calcium (r:0.26,p:0.035), and c-f25(OH)D (r:0.553,p:0.016); and inversely with iPTH (r:-0.374, p:0.002), alkaline phosphatase (r:-0.28, p:0.026), and age (r:-0.289, p:0.018). Total 25(OH)D correlated with the same parameters as m-f25(OH)D except for serum calcium. However, c-f25(OH)D correlated only with total 25(OH)D and VDBP, both included in the calculation formula.Multiple regression analysis showed that m-f25(OH)D variations were independently explained by calcium (β:0.156, p:0.026) and total 25(OH)D (β:0.043, p < .001).The optimal m-f25(OH)D cut-off for discriminating between insufficient and sufficient total 25(OH)D was >9.8 pmol/L (Area Under Curve (AUC): 0.897 (95% confidence interval (CI): (0.798–0.958); p < .001; sensitivity:72.7% (95%CI: 49.8–89.3); specificity: 95.5% (95%CI: 84.5–99.4)).ConclusionsDirectly measured free vitamin D correlated better with markers of phosphocalcic metabolism than total 25(OH)D and c-f25(OH)D in a population of healthy children.     

Distribution and correlates of serum 25-hydroxyvitamin D levels in a sample of patients with hip fracture

Background: Vitamin D deficiency is common in older populations, particularly during the winter months due to low levels of ultraviolet light exposure, and in nursing home residents.Objective: The main objective of the current study was to assess the distribution of serum 25-hydroxyvitamin D and its correlates in a sample of men and women with recent hip fractures who were part of a large clinical trial.Methods: This was a cross-sectional exploratory study of screened and ultimately randomized patients with hip fractures. They were part of a multinational (115 clinical centers in 20 countries), randomized, placebo-controlled, double-blind study testing the efficacy of a yearly IV bisphosphonate (zoledronic acid) in the prevention of new clinical fractures in patients with recent hip fracture repair. Levels of 25-hydroxyvitamin D, calcium, alkaline phosphatase, creatinine clearance, and albumin were measured at a screening visit using blood serum. Demographic variables were assessed by patient self-report. Bone mineral density (BMD) was assessed by dual-energy x-ray absorptiometry of the nonfracturcd hip.Results: This report included 1174 screened patients (526 with vitamin D measured) and 655 (385 with vitamin D measured) patients randomized before the protocol amendment. In screened patients, levels of 25-hydroxyvitamin D wcrc low (median, 14.7 ng/mL; interquartilc range, 7.6, 21.65). Overall, 51% were at or below the clinically meaningful threshold of 15 ng/mL. Among those patients randomized, the level of 25-hydroxyvitamin D was significantly positively related to male sex (ρ, 0.13; P < 0.05), serum calcium (ρ, 0.16; P < 0.01), and BMD at the femoral neck (ρ, 0.22; P < 0.01) in bivariate analyses. Low serum 25-hydroxyvitamin D (<15 ng/mL) was related only to low serum calcium (odds ratio, 0.16; 95% CI, 0.05-0.52) in multivariable logistic models controlling for sex, age, race, body mass index, living at home, alkaline phosphatase, and creatinineclearance.Conclusions: We concluded that vitamin D insufficiency was a common problem in this population of elderly patients who had recently suffered a hip fracture. This insufficiency was related only to serum calcium in multivariable controlled models but cannot be reliably identified or excluded by measuring serum calcium alone. Physicians should be encouraged to check and monitor patients' serum levels of 25-hydroxyvitamin D.     

Measurement of vitamin D status: background, clinical use, and methodologies

Vitamin D and its metabolites are crucial to the overall health and well-being of humans and animals, having important functions in calcium homeostasis and bone metabolism. Exposure of the skin to sunlight may provide adequate levels of vitamin D; however, there are numerous reports of vitamin D insufficiency or deficiency. 25-hydroxyvitamin D (calcidiol, 25(OH)D) is regarded as the best measurement of overall vitamin D status. 1,25-dihydroxyvitamin D (calcitriol, 1,25(OH)2D) is the most biologically active vitamin D metabolite. 25(OH)D has higher affinity for vitamin D binding protein (VDBP) than 1,25-dihydroxyvitamin D; whereas, 1,25-dihydroxyvitamin D has higher affinity for the vitamin D receptor (VDR) than 25-hydroxyvitamin D. HPLC and immunoassays allow the determination of vitamin D status, as measured by 25(OH)D, and 1,25(OH)2D. Recently it has been shown that the vitamin D requirements have been underestimated and that vitamin D2 is much less potent than vitamin D3. Future studies will determine the amount of vitamin D3 necessary for optimal health and well-being.