The role of vitamin D in the prevention of osteoporosis

The need for vitamin D to prevent rickets was the drive for selection of lighter skin color in temperate climates. Anthropologists also know that as human populations developed more sedentary lifestyles, this coincided with a decline in bone quantity, quality, and fracture resistance. Since osteoporosis occurs after the reproductive years, there is no way that natural selection could have adapted our biology to prevent it. However, osteoporosis can be largely prevented by optimizing physical activity, and the vitamin D-related factors of environment, and nutrition. The role of vitamin D3 in osteoporosis is conclusively established from a very simple meta-analysis of the four randomized, placebo-controlled clinical trials into the effect of 20 microg (800 IU) per day. These have all demonstrated that this dose prevents approximately 30% of hip or non-vertebral fractures compared to placebo, in adults older than 65 years. Intakes less than this have never been found effective. The lowest average serum 25-hydroxyvitamin D concentration in any study demonstrating fracture reduction was 74 nmol/L. Thus, 25-hydroxyvitamin D levels in older adults should exceed this amount. The role of vitamin D supplementation is to provide humans with the nutrient in an amount closer to our species' biological norm. This amount of vitamin D results in the optimal function of many aspects of health, including balance and muscle strength that lessen the risk of fracture beyond what is possible via the quality and quantity of bone itself.     

围绝经期妇女血清维生素D水平与骨质疏松的相关性研究

目的：探讨深圳市龙岗地区围绝经期妇女维生素D水平与骨质疏松的关系。方法收集2012年8月至2013年8月参加体检的围绝经期妇女血清，采用串联质谱法检测血清维生素D、维生素D2及维生素D3水平，并使用双能X线吸收仪（DEXA）测定髋部及L1～4的骨密度。结果435例受试者中，血清维生素D水平缺乏情况普遍存在，且以维生素D3缺乏为主；严重缺乏组左侧股骨颈骨密度为（0．623±0．087）g/cm^2，明显低于维生素D不足组的（0．726±0．091）g/cm^2及充足组的（0．731±0．089）g/cm^2（P＜0．05）；wards三角骨密度为（0．391±0．054）g/cm^2，明显低于维生素D不足组的（0．492±0．061）g/cm^2及充足组的（0．524±0．075）g/cm^2，3个年龄组的左侧股骨颈、wards三角、L1～4、大粗隆、大转子区及左侧股骨上端骨密度均随着年龄增大而逐渐降低，差异有统计学意义（P＜0．05）。结论深圳龙岗地区围绝经期妇女普遍缺乏维生素D，需要加强宣教，低维生素D水平与骨骼中某些部位的低骨密度相关。     

壮骨胶囊及碳酸钙和维生素D治疗老年性骨质疏松的效果比较

目的:筛选与评价安全、有效、可长期口服的防治骨质疏松(O)药物。P方法:分别用中药壮骨胶囊及西药碳酸钙和维生素D治疗45例老年性OP患者,选择骨密度(BMD及被测骨密度与同性别年轻人峰值骨之差)别(T)值、血清骨钙素(BG、降钙素P)(CT)、雌二醇(E2)、碱性磷酸酶(A)、钙(C)、磷(P)等为观察指标。KPa结果:中药治疗前29例老年性OP患者的BMD及血清CT,E2分别为(0.79±0.13)g/cm10.91±10.28)pmol/L2,(及(28.16±16.70)pmol/L;而治疗后则分别为(0.84±0.13)g/cm2,(29.41±36.45)pmol/L及(48.28±18.85)pmol/L,治疗后均升高,较治疗前差异均有非常显著性意义P<0.01)(。西药治疗前16例老年性OP患者的BMD,BGP分别为0.74±0.18)g/cm及5.05±2.60)μg/L,而治疗后则分别为(2((0.77±0.14)g/cm2及(6.29±2.42)μg/L,治疗后亦升高,较治疗前差异均有显著性意义(P<0.05)。其中中药治疗后较治疗前BMD平均上升6.6%,T平均上升0.44,OP的分度明显改善;而西药治疗后较治疗前升高5.0%,T平均上升0.27,OP的分度轻微改善。血AKP,Ca,P两组治疗前后差异无显著性意义。治疗前Ⅲ度OP患者的BMD明显低于Ⅰ,Ⅱ度。中药治疗后Ⅱ,Ⅲ度OP患者的BMD低于Ⅰ度。结论:中药壮骨胶囊及西药碳酸钙和维生素D对老年性OP治疗均有效,前者疗效似更好。     

Abnormal vitamin D metabolism in patients with cirrhosis.

To assess the role of hepatic function and alcohol on vitamin D metabolism, serum 25-hydroxyvitamin D (25-OHD) levels were measured in 20 healthy nonalcoholic control subjects, 31 "inactive" cirrhotics whose alcoholism was in remission, 8 alcoholic cirrhotics, and 15 alcoholics with normal liver function. Cirrhosis but not alcoholism, was assoicated with low serum 25-OHD levels. The aminopyrine breath test (ABT) was performed because aminopyrine, like vitamin D3, is metabolized by hepatic microsomes; the ABT correlated highly (r = 0.74, rho less than 0.01) with serum 25-OHD in the inactive cirrhotics. After an intravenous injection of 120 mug vitamin D3, serum 25-OHD rose significantly within 24 hr in 6 healthy controls and 2 patients with celiac disease but not in 6 inactive cirrhotics. The data suggest impaired 25-hydroxylation of vitamin-D impaired in patients with cirrhosis, related predominantly to the degree of hepatic dysfunction.     

The role of the liver in the metabolism of vitamin D

The metabolism of vitamin D(3) has been studied after intravenous injection of 10 IU of [1,2-(3)H]-vitamin D(3) to vitamin D-deficient rats. The disappearance of the radioactivity from the plasma follows a very peculiar pattern characterized by an early rapid disappearance followed by a rebound of radioactivity before assuming still a third rather slow disappearance rate. The "rebound" phenomenon is concomitant with a rapid release of the radioactivity from the liver and is accounted for by the appearance of 25-hydroxycholecalciferol and other metabolites in the blood. It is postulated that the liver is the major site of transformation of vitamin D(3) into 25-hydroxycholecalciferol.     

重庆地区骨质疏松患者25-羟维生素D与骨代谢的相关性分析

目的对25-羟维生素D和甲状旁腺激素(PTH)、N端骨钙素(N-MID)、降钙素(CT)、骨碱性磷酸酶(BALP)的相关性进行统计学分析,并探讨其在临床疾病的诊断、预防及治疗中的应用价值。方法收集2014年1-9月重庆医科大学附属第二医院住院患者411例,其中女316例,男95例;平均(69.29±12.21)岁。采用免疫电化学发光法检测住院患者25-羟维生素D、PTH、N-MID、CT、BALP的水平,探讨骨质疏松患者25-羟维生素D与骨代谢标志物的关系。结果25-羟维生素D与PTH、BALP均呈负相关关系(P0.05),而与CT、N-MID则无显著相关(P0.05)。回归分析显示,25-羟维生素D与骨代谢标志物回归方程为Y=19.02-0.066PTH-0.09BALP。结论骨质疏松患者25-羟维生素D水平的升高、降低与PTH、BALP均有一定相关性,通过对这些指标的检测,可以为临床骨质疏松患者的诊断、预防和控制提供基础数据。     

Risk factors for vitamin D inadequacy among women with osteoporosis: an international epidemiological study

A serum 25-hydroxyvitamin D [25(OH)D] level of 75 nmol/l (30 ng/ml) has been proposed as the minimum for adequate vitamin D nutrition as lower levels are associated with increases in serum parathyroid hormone in otherwise healthy adults. Amongst 2589 community-dwelling, postmenopausal women with osteoporosis from 18 countries, recruited to determine risk factors for vitamin D inadequacy, 64% had vitamin D inadequacy. General health, education, ethnicity, sun exposure, skin reactivity, diet, recent travel to sunny climates, vitamin D supplementation, body mass index (BMI), season and latitude were assessed using logistic regression models. Asian ethnicity, BMI >or=30 kg/m(2), living in non-equatorial countries, inadequate vitamin D supplementation, poor/fair health, no education about vitamin D, skin reactivity and no recent travel to sunny areas were significant predictors. Several modifiable risk factors are associated with vitamin D inadequacy worldwide, suggesting potentially simple ways to increase vitamin D and improve bone health in postmenopausal women.     

Assessment of vitamin D status in male osteoporosis

BACKGROUND: Clinical assessment of vitamin D status often relies on measuring total circulating 25-hydroxyvitamin D3 (25OHD3), 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 DBP 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 25OHD3 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)2D3 measured in randomly selected men with osteoporosis (n = 50) and controls (n = 50) was 90 (37) and 103 (39) pmol/L, respectively. Mean plasma DBP 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 DBP, rather than total circulating vitamin D metabolites, may provide a more useful index of biological activity. Further studies are required to substantiate this hypothesis.     

钙剂和维生素D在老年骨质疏松症中的应用

随着人口老龄化日趋严重,骨质疏松症已经成为我国面临的重要公共健康问题。骨质疏松症是一种多见于绝经后女性和老年男性,以骨量低下、骨组织微结构损坏,导致骨脆性增加,易发生骨折为特征的全身性代谢性骨病。钙剂和维生素D作为骨健康基本补充剂,在骨质疏松症的防治中具有重要作用。该文就老年骨质疏松症患者钙剂和维生素D应用中的相关问题进行阐述。     

碱性磷酸酶同工酶在老年女性骨质疏松诊断中的应用

目的 探讨碱性磷酸酶（ALP）同工酶在老年女性骨质疏松诊断中的应用。方法 采用神经氨酸苷酶,用琼脂糖电泳法对体检正常者50例（对照组）和老年女性骨质疏松患者55例（骨质疏松组）血清中的ALP同工酶进行分离分析。结果 经神经氨酸苷酶处理后,琼脂糖电泳法可以分离肝和骨ALP;两组肝型ALP比较,差异无显著性意义（P〉0.05）;骨型ALP比较,差异有显著性意义（P〈0.05）;热失活法和电泳法检测骨ALP具有显著的相关关系（r=0.92,P〈0.05）。结论 骨型ALP可为临床诊断老年女性骨质疏松提供可靠的依据。     

钙及维生素D3治疗中老年女性骨质疏松症的临床研究

目的观察钙及活性维生素D3(VitD3)在治疗中老年女性骨质疏松症中的疗效。方法 300例中老年女性骨质疏松症患者随机分成钙和VitD3组与钙剂组,治疗2年,钙加VitD3组采用钙尔奇D联合骨化三醇治疗,钙剂组采用钙尔奇D治疗。结果两组生活能力明显提高,双手握力增加(P<0.01)。钙剂组患者经过治疗后腰椎、股骨大转子骨密度增加(P<0.01),股骨颈骨密度降低;钙加VitD3组全部骨密度降低。结论钙及VitD3在治疗中老年女性骨质疏松症中对改善临床症状疗效良好。     

糖尿病患者维生素D受体基因多态性与骨质疏松的相关性

目的:观察糖尿病患者与正常人之间以及不同骨量的糖尿病患者之间维生素D受体基因型的分布差异。方法:选自青岛市内分泌糖尿病研究所内分泌科1998-09/2001-01住院糖尿病患者122例为糖尿病组,诊断参照WHO1999年新标准,并且除外重度吸烟、嗜酒者、肾功能损害者及服用影响骨代谢药物者。2型糖尿病组68例,1型糖尿病组54例。以中国骨质疏松症建议诊断标准为依据诊断骨质疏松和骨量减少。糖尿病组骨量正常58例(男/女=33/25),骨量减少30例(男/女=15/15),骨质疏松34例(男/女=17/17)。并以青岛市内分泌糖尿病研究所62名体检健康成年人为对照组,采用聚合酶链反应限制性片段长度多态性技术对其进行维生素D受体,基因(A-paI,TaqI位点)型检测,并计算其基因分布频率。结果:①1型糖尿病组、2型糖尿病组与健康人维生素D受体基因型分布频率的比较1型糖尿病组Tt基因型的分布频率有增高趋势(1型糖尿病组14.8%,2型糖尿病组7.4%,对照组4.8%,P=0.068)。②维生素D受体基因多态性与糖尿病性骨质疏松的相关性:在糖尿病患者群中,aa基因型在骨量减少和骨质疏松患者中分布频率显著高于糖尿病骨量正常者(骨量减少组63.3%,骨质疏松组73.5%,骨量正常组41.3%,P<0.05),Aa基因型分布频率显著低于骨量正常者(骨量减少组26.7%,骨质疏松组26.5%,骨量正常组44.8%,P<0.05),糖尿病骨质疏松患者中未检出AA基因型。结论:在糖尿患者群中,维生素D受体基因分布与健康人差异不显著。糖尿病患者对应于ApaI酶切位点的维生素D受体基因多态与骨质疏松存在相关性,对应于TaqI酶切位点的维生素D受体基因多态与1型糖尿病的发生有相关趋势,对糖尿病骨质疏松的发生有一定的预测价值。