Mosekilde Leif
Department of Endocrinology and Metabolism C, Aarhus University Hospital, Aarhus C, Denmark.
Clin Endocrinol (Oxf). 2005 Mar;62(3):265-81. doi: 10.1111/j.1365-2265.2005.02226.x.
This review summarizes current knowledge on vitamin D status in the elderly with special attention to definition and prevalence of vitamin D insufficiency and deficiency, relationships between vitamin D status and various diseases common in the elderly, and the effects of intervention with vitamin D or vitamin D and calcium. Individual vitamin D status is usually estimated by measuring plasma 25-hydroxyvitamin D (25OHD) levels. However, reference values from normal populations are not applicable for the definition of vitamin D insufficiency or deficiency. Instead vitamin D insufficiency is defined as the lowest threshold value for plasma 25OHD (around 50 nmol/l) that prevents secondary hyperparathyroidism, increased bone turnover, bone mineral loss, or seasonal variations in plasma PTH. Vitamin D deficiency is defined as values below 25 nmol/l. Using these definitions vitamin D deficiency is common among community-dwelling elderly in the developed countries at higher latitudes and very common among institutionalized elderly, geriatric patients and patients with hip fractures. Vitamin D deficiency is an established risk factor for osteoporosis, falls and fractures. Clinical trials have demonstrated that 800 IU (20 microg) per day of vitamin D in combination with 1200 mg calcium effectively reduces the risk of falls and fractures in institutionalized patients. Furthermore, 400 IU (10 microg) per day in combination with 1000 mg calcium or 100 000 IU orally every fourth month without calcium reduces fracture risk in individuals over 65 years of age living at home. Yearly injections of vitamin D seem to have no effect on fracture risk probably because of reduced bioavailability. Simulation studies suggest that fortification of food cannot provide sufficient vitamin D to the elderly without exceeding present conventional safety levels for children. A combination of fortification and individual supplementation is proposed. It is argued that all official programmes should be evaluated scientifically. Epidemiological studies suggest that vitamin D insufficiency is related to a number of other disorders frequently observed among the elderly, such as breast, prostate and colon cancers, type 2 diabetes, and cardiovascular disorders including hypertension. However, apart from hypertension, causality has not been established through randomized intervention studies. It seems that 800 IU (20 microg) vitamin D per day in combination with calcium reduces systolic blood pressure in elderly women.
本综述总结了目前关于老年人维生素D状况的知识，特别关注维生素D不足和缺乏的定义及患病率、维生素D状况与老年人常见的各种疾病之间的关系，以及维生素D或维生素D与钙干预的效果。个体维生素D状况通常通过测量血浆25-羟基维生素D（25OHD）水平来评估。然而，正常人群的参考值不适用于维生素D不足或缺乏的定义。相反，维生素D不足被定义为预防继发性甲状旁腺功能亢进、骨转换增加、骨矿物质流失或血浆甲状旁腺激素季节性变化的血浆25OHD最低阈值（约50 nmol/l）。维生素D缺乏定义为低于25 nmol/l的值。根据这些定义，在高纬度发达国家的社区老年人中，维生素D缺乏很常见，在机构养老的老年人、老年患者和髋部骨折患者中非常普遍。维生素D缺乏是骨质疏松症、跌倒和骨折的既定危险因素。临床试验表明，每天800 IU（20微克）维生素D联合1200毫克钙可有效降低机构养老患者跌倒和骨折的风险。此外，每天400 IU（10微克）联合1000毫克钙或每四个月口服100 000 IU维生素D（不补钙）可降低65岁以上居家老年人的骨折风险。每年注射维生素D似乎对骨折风险没有影响，可能是因为生物利用度降低。模拟研究表明，在不超过目前儿童常规安全水平的情况下，食物强化不能为老年人提供足够的维生素D。建议采用强化和个体补充相结合的方法。有人认为，所有官方项目都应进行科学评估。流行病学研究表明，维生素D不足与老年人中经常观察到的许多其他疾病有关，如乳腺癌、前列腺癌和结肠癌、2型糖尿病以及包括高血压在内的心血管疾病。然而，除了高血压外，尚未通过随机干预研究确定因果关系。每天800 IU（20微克）维生素D联合钙似乎可降低老年女性的收缩压。
