25-Hydroxyvitamin D: functional outcomes in infants and young children

Vitamin D deficiency occurs in the United States in exclusively breastfed infants who have high levels of skin pigmentation, inadequate vitamin D supplementation, and insufficient sunlight exposure. I review serum 25-hydroxyvitamin D [25(OH)D] concentrations and functional outcomes of vitamin deficiency in young children and breastfed and nonbreastfed infants. These outcomes include the presence or absence of vitamin D deficiency rickets, bone mineral content, and serum parathyroid hormone concentration. Daily vitamin D supplements of 400 IU/L keep serum 25(OH)D concentrations higher than 50 nmol/L and prevent rickets in infants and young children. The available evidence is not sufficient to support the use of bone mineral content or parathyroid hormone concentrations in infants and young children as functional outcomes to define deficient or sufficient levels of 25(OH)D. I therefore propose a research agenda to establish the functional definitions of vitamin D sufficiency or deficiency in infants and young children.     

25(OH)Vitamin D Deficiency and Calcifediol Treatment in Pediatrics

Vitamin D is essential for the normal mineralization of bones during childhood. Although diet and adequate sun exposure should provide enough of this nutrient, there is a high prevalence of vitamin D deficiency rickets worldwide. Children with certain conditions that lead to decreased vitamin D production and/or absorption are at the greatest risk of nutritional rickets. In addition, several rare genetic alterations are also associated with severe forms of vitamin-D-resistant or -dependent rickets. Although vitamin D3 is the threshold nutrient for the vitamin D endocrine system (VDES), direct measurement of circulating vitamin D3 itself is not a good marker of the nutritional status of the system. Calcifediol (or 25(OH)D) serum levels are used to assess VDES status. While there is no clear consensus among the different scientific associations on calcifediol status, many clinical trials have demonstrated the benefit of ensuring normal 25(OH)D serum levels and calcium intake for the prevention or treatment of nutritional rickets in childhood. Therefore, during the first year of life, infants should receive vitamin D treatment with at least 400 IU/day. In addition, a diet should ensure a normal calcium intake. Healthy lifestyle habits to prevent vitamin D deficiency should be encouraged during childhood. In children who develop clinical signs of rickets, adequate treatment with vitamin D and calcium should be guaranteed. Children with additional risk factors for 25(OH)D deficiency and nutritional rickets should be assessed periodically and treated promptly to prevent further bone damage.     

The vitamin D epidemic and its health consequences

Vitamin D deficiency is now recognized as an epidemic in the United States. The major source of vitamin D for both children and adults is from sensible sun exposure. In the absence of sun exposure 1000 IU of cholecalciferol is required daily for both children and adults. Vitamin D deficiency causes poor mineralization of the collagen matrix in young children's bones leading to growth retardation and bone deformities known as rickets. In adults, vitamin D deficiency induces secondary hyperparathyroidism, which causes a loss of matrix and minerals, thus increasing the risk of osteoporosis and fractures. In addition, the poor mineralization of newly laid down bone matrix in adult bone results in the painful bone disease of osteomalacia. Vitamin D deficiency causes muscle weakness, increasing the risk of falling and fractures. Vitamin D deficiency also has other serious consequences on overall health and well-being. There is mounting scientific evidence that implicates vitamin D deficiency with an increased risk of type I diabetes, multiple sclerosis, rheumatoid arthritis, hypertension, cardiovascular heart disease, and many common deadly cancers. Vigilance of one's vitamin D status by the yearly measurement of 25-hydroxyvitamin D should be part of an annual physical examination.     

Vitamin D deficiency: a worldwide problem with health consequences

Vitamin D deficiency is now recognized as a pandemic. The major cause of vitamin D deficiency is the lack of appreciation that sun exposure in moderation is the major source of vitamin D for most humans. Very few foods naturally contain vitamin D, and foods that are fortified with vitamin D are often inadequate to satisfy either a child's or an adult's vitamin D requirement. Vitamin D deficiency causes rickets in children and will precipitate and exacerbate osteopenia, osteoporosis, and fractures in adults. Vitamin D deficiency has been associated with increased risk of common cancers, autoimmune diseases, hypertension, and infectious diseases. A circulating level of 25-hydroxyvitamin D of >75 nmol/L, or 30 ng/mL, is required to maximize vitamin D's beneficial effects for health. In the absence of adequate sun exposure, at least 800-1000 IU vitamin D3/d may be needed to achieve this in children and adults. Vitamin D2 may be equally effective for maintaining circulating concentrations of 25-hydroxyvitamin D when given in physiologic concentrations.     

HPLC-MS/MS法检测吉林省427例儿童血浆25(OH)D的水平

目的:了解吉林省保健体检儿童血浆25(OH)D的水平,探讨高效液相色谱-串联质谱法(HPLC-MS/MS法)诊断维生素D缺乏性佝偻病的临床意义。方法:采用HPLC-MS/MS法检测并分析了427例体检儿童血浆25(OH)D的水平。结果:①血浆25(OH)D属于正常参考值范围的检出率为41.69%(178/427);低于正常参考值范围的检出率为58.31%(249/427),其中血浆25(OH)D处于缺乏水平的检出率为28.34%(121/427),处于不足水平的检出率为29.98%(128/427);高于正常参考值的检出率为0.00%(0/427)。②255例0～3岁研究对象中,1岁以内婴儿25(OH)D缺乏的发病率为39.34%(24/61),13个月～3岁幼儿25(OH)D缺乏的发病率为15.46%(30/194),二者相比有统计学差异(χ2=15.854 9,P=6.84E-5)。③临床诊断为佝偻病的121例儿童血浆25(OH)D检测结果占全部低于正常参考值儿童的48.59%(121/249),而血浆25(OH)D检测值低于正常参考值但临床尚未诊断佝偻病的儿童占全部低于正常参考值儿童的51.41%(128/249)。结论:①维生素D不足在吉林省的发病率高(58.31%),尤其1岁内婴儿更容易罹患维生素D缺乏,必须进一步加强和规范吉林省佝偻病的防治工作。②目前临床诊断佝偻病与经HPLC-MS/MS法检测25(OH)D诊断佝偻病符合率约50%,应尽快广泛普及此法,提高诊断的敏感性和特异性。     

维生素D缺乏性佝偻病影响因素的研究

目的 探讨佳木斯地区0～2岁婴幼儿佝偻病的影响因素,为佝偻病的干预提供依据.方法 整群抽取0～2岁临床上有活动期维生素D缺乏性佝偻病症状和体征的婴幼儿159例,同时随机抽取78例0～2岁正常婴幼儿作为对照组.在填写家庭、社会和营养因素调查表的同时进行相应的体格及实验室检查.结果 单因素分析:佝偻病的发生与母孕期每天日照时间、婴幼儿年龄、每天乳制品的摄入量、每天日照时间、是否患有慢性腹泻等疾病、体重、身高等7个变量显著相关.多因素逐步回归分析:母孕期每天日照时间、婴幼儿出生体重、出生身长、出生后至调查时是否补充维生素D、每天乳制品摄入量及每天日照时间,与佝偻病的发生显著相关.结论 母孕期每天日照时间短、婴幼儿年龄小、出生体重重、出生身长短、出生后未及时补充维生素D、每天乳制品摄入量过少及每天日照时间短,是佝偻病发生的危险因素.     

Maternal vitamin D status: effect on milk vitamin D content and vitamin D status of breastfeeding infants

There are increasing reports of rickets and vitamin D deficiency worldwide. Breastfeeding without adequate sunlight exposure and vitamin D supplementation are the major risk factors. In view of the drive to promote and increase the rate of exclusive breastfeeding, the relationship among maternal vitamin D status, vitamin D concentration of human milk, and hence vitamin D status of breastfeeding infants deserves reassessment. This review provides current information on the interrelationship between maternal vitamin D status and the vitamin D status of the breastfeeding infant. It also reviews the results of ongoing research on the effect of high-dose maternal vitamin D supplementation alone as a possible option to prevent vitamin D deficiency in the breastfeeding mother-infant dyad.     

An Update on Vitamin D Deficiency Status in Malaysia

Vitamin D is essential for maintaining serum calcium levels, ensuring sufficient bone mineralization, immunomodulatory properties, and a protective effect on the cardiovascular system, renal disease, cancer, as well as in pregnancy. Vitamin D deficiency is prevalent worldwide, and it is not related to a country’s development index. However, the data on vitamin D deficiencies are primarily taken from out-of-date, small-scale studies on target age groups or specific diseases, rather than from large-scale, population-based surveys. In Malaysia, for the past 16 years, studies were conducted involving adult men and women, pregnant women, postmenopausal women, adolescent, and children especially with specific diseases such as spina bifida, epilepsy, chronic liver disease, and atopic dermatitis. Only a few large surveys were conducted involving children and adolescents. Across the specific target population studied, vitamin D deficiency and insufficiency were seen particularly among females, Indians, and those of Malay ethnicity. This is related to widely known causes of vitamin D deficiency such as skin type (melanin) and sun avoidant lifestyles that include covering clothes, largely practiced by Malay Muslims in Malaysia. Other related causes or the high-risk groups are breastfed infants, the elderly, the obese, those on medications, and those characterized by fat malabsorption and geophysical factors. Vitamin D deficiency can be managed with pharmacological or non-pharmacological approaches, depending on the severity. The objective is to raise serum vitamin D to a normal level, hence, relieving the symptoms and reducing the adverse health outcomes. Despite no clear guidelines in treating vitamin D deficiency in Malaysia, this condition can be prevented with taking adequate vitamin D in food resources, sun exposure, or supplementation. Special attention should be given to high-risk groups including infants, obese patients, and the elderly.     

The ABC of Vitamin D: A Qualitative Study of the Knowledge and Attitudes Regarding Vitamin D Deficiency amongst Selected Population Groups

Objective: In Australia, vitamin D supply in food is limited, and sun exposure is the main source of vitamin D. However skin cancer risk is high, and the need to gain some sun exposure for adequate vitamin D is challenging public health messages to use protection in the sun. The complex vitamin D public health message may be confusing the public and, in particular, those at highest risk for vitamin D deficiency. This study explored vitamin D and sun exposure attitudes, knowledge and practices of some groups considered at risk of vitamin D deficiency and those delivering healthy sun exposure messages to children. Method: 52 adults participated in six focus groups. Results: Results corroborated with previous research showing low levels of vitamin D knowledge. Individual and environmental barriers to receiving adequate sun exposure were also identified. Conclusions and Implications: The message advocating balanced sun exposure to produce adequate vitamin D needs to be made clearer and be more effectively communicated. Findings provide insights to aid development of appropriate public health messages for safe sun exposure and vitamin D, especially for vulnerable groups.     

The high prevalence of vitamin D insufficiency across Australian populations is only partly explained by season and latitude

BACKGROUND: Inadequate sun exposure and dietary vitamin D intake can result in vitamin D insufficiency. However, limited data are available on actual vitamin D status and predictors in healthy individuals in different regions and by season. METHODS: We compared vitamin D status [25-hydroxyvitamin D; 25(OH)D] in people < 60 years of age using data from cross-sectional studies of three regions across Australia: southeast Queensland (27 degrees S; 167 females and 211 males), Geelong region (38 degrees S; 561 females), and Tasmania (43 degrees S; 432 females and 298 males). RESULTS: The prevalence of vitamin D insufficiency (相似文献   

Dietary recommendations for vitamin D: a critical need for functional end points to establish an estimated average requirement

From its inaugural value in 1941, the Recommended Dietary Allowance (RDA) for adults for vitamin D has remained close to 400 IU (10 microg) level. This original recommended intake was based on the observation that the amount of vitamin D activity in a teaspoon of cod liver oil was sufficient to prevent rickets in infants. Since that time until 1997, determination of vitamin D requirements and status was more conjecture than science. In 1997, when the recommended intake level of vitamin D was set as an adequate intake value rather than an RDA, much has been learned about metabolism of vitamin D. The circulating metabolite 25-hydroxyvitamin D is the major static indicator of vitamin D status. Using its response to diet in the absence of sun exposure, a dose-response study suggests a mean requirement of at least 500 IU (12.5 microg) from which an RDA could be set. Other factors may need adjustment, such as sun exposure and body fat. However, functional indicators of status are needed. The role of vitamin D in calcium metabolism (i.e., calciotropic functions) is better understood; bone turnover and parathyroid hormone are potential indicators. Vitamin D has noncalciotropic functions arising from extrarenal synthesis of the active metabolite 1,25 dihydroxyvitamin D involving cell proliferation and immunity, from which function indicators of status may be derived. Despite gaps in our knowledge, there are data from which new dietary reference intake values for vitamin D may be set.     

Vitamin D status and its adequacy in healthy Danish perimenopausal women: relationships to dietary intake, sun exposure and serum parathyroid hormone

We conducted this study to assess the prevalence of vitamin D insufficiency in a population of normal perimenopausal women, to examine the influence of sun exposure and vitamin D intake on the concentration of 25-hydroxyvitamin D (25OHD) and to examine the association between parathyroid hormone (PTH) and 25OHD. A total of 2016 healthy women aged 45-58, who had recently undergone a natural menopause, were enrolled over a 2.5-year period in the Danish Osteoporosis Prevention Study. A marked seasonal fluctuation of 25OHD was seen, with an abrupt rise in June and high values until October. The fluctuation could be related to number of hours of sunshine per month with a two months time lag. Dietary vitamin D intake, vitamin supplementation, sunlight exposure, and use of sun-bed were all significantly related to 25OHD concentrations. Sun exposure seemed to contribute the most. The overall prevalence of vitamin D deficiency (defined as serum ) was 7 %. However, in the subgroup avoiding direct sunshine and abstaining from vitamin D supplementation 32.8 % were vitamin D deficient in the winter-spring period. Although mean PTH was increased in the group with low serum 25OHD, PTH was not a sensitive marker of hypovitaminosis D in the individual, as only 16 % of those with vitamin D deficiency had PTH levels above normal range. Thus, we have shown, that healthy middle-aged Danish women are prone to vitamin D insufficiency in the winter-spring period, if they avoid sun exposure in the summer period and abstain from vitamin D supplementation.     

Sun exposure and vitamin D sufficiency

Ultraviolet radiation is a carcinogen that also compromises skin appearance and function. Because the ultraviolet action spectra for DNA damage, skin cancer, and vitamin D(3) photosynthesis are identical and vitamin D is readily available from oral supplements, why has sun protection become controversial? First, the media and, apparently, some researchers are hungry for a new message. Second, the controversy is fueled by a powerful special interest group: the tanning industry. This industry does not target the frail elderly or inner-city ethnic minorities, groups for whom evidence of vitamin D(3) insufficiency is strongest, but rather fair-skinned teenagers and young adults, who are at highest risk of ultraviolet photodamage. Third, evolution does not keep pace with civilization. When nature gave humans the appealing capacity for cutaneous vitamin D(3) photosynthesis, life expectancy was <40 y; long-term photodamage was not a concern; and vitamin D(3) deficiency, with its resulting skeletal abnormalities (rickets), was likely to be fatal in early life. In the 21st century, life expectancy approaches 80 y in developed countries, vitamin D(3) is available at the corner store, and the lifetime risk of skin cancer is 1 in 3 among white Americans. Medical and regulatory groups should avoid poorly reasoned, sensationalistic recommendations regarding unprotected ultraviolet exposure. Instead, they should rigorously explore possible cause-and-effect relations between vitamin D(3) status and specific diseases while advocating the safest possible means of ensuring vitamin D(3) sufficiency.     

Vitamin D status of infants in northeastern rural Bangladesh: preliminary observations and a review of potential determinants

Vitamin D deficiency is a global public-health concern, even in tropical regions where the risk of deficiency was previously assumed to be low due to cutaneous vitamin D synthesis stimulated by exposure to sun. Poor vitamin D status, indicated by low serum concentrations of 25-hydroxyvitamin D [25(OH)D], has been observed in South Asian populations. However, limited information is available on the vitamin D status of young infants in this region. Therefore, to gain preliminary insights into the vitamin D status of infants in rural Bangladesh, 25(OH)D was assessed in a group of community-sampled control participants in a pneumonia case-control study in rural Sylhet, Bangladesh (25 degrees N) during the winter dry season (January-February). Among 29 infants aged 1-6 months, the mean 25(OH)D was 36.7 nmol/L [95% confidence interval (CI) 30.2-43.2]. The proportion of infants with vitamin D deficiency defined by 25(OH)D < 25 nmol/L was 28% (95% CI 10-45), 59% (95% CI 40-78) had 25(OH)D < 40 nmol/L, and all were below 80 nmol/L. From one to six months, there was a positive correlation between age and 25(OH)D (Spearman = 0.65; p = 0.0001). Within a larger group of 74 infants and toddlers aged 1-17 months (cases and controls recruited for the pneumonia study), young age was the only significant risk factor for vitamin D deficiency [25(OH)D < 25 nmol/L]. Since conservative maternal clothing practices (i.e. veiling) and low frequency of intake of foods from animal source (other than fish) were common among the mothers of the participants, determinants of low maternal-infant 25(OH)D in Bangladesh deserve more detailed consideration in future studies. In conclusion, the vitamin D status in young infants in rural Sylhet, Bangladesh, was poorer than might be expected based on geographic considerations. The causes and consequences of low 25(OH)D in infancy and early childhood in this setting remain to be established.     

Rickets during extended total parenteral nutrition in a boy with a VIP-producing ganglioneuroma and the WDHA syndrome

A four-month-old boy was operated on for a retroperitoneal neuroblastoma, stage IV-S. Six months later he developed the WDHA syndrome and was treated with total parenteral nutrition (TPN) for the following 18 months. The tumour had transformed into a ganglioneuroma which produced vasoactive intestinal peptide. After nine months of TPN he developed rickets, despite the fact that a recommended daily dose of vitamin D had been given. The rickets healed after the addition of therapeutic doses of vitamin D and an oral calcium phosphate supplement. The vitamin D status of children receiving long-term TPN should be monitored. Higher doses of vitamin D than are generally recommended may be necessary during long-term TPN in infants and young children. The calcium and phosphorus contents of standard TPN regimens in such cases may also be insufficient.     

银川吴忠两市儿童青少年维生素D营养状况

了解宁夏银川、吴忠两市儿童青少年维生素D营养状况,为预防儿童青少年维生素D不足与缺乏提供合理依据.方法 在银川市2区和吴忠市随机抽取小学、初中和高中,采用分层整群抽样的方法抽取班级.排除佝偻病、克罗恩病、心血管疾病及肝肾疾病患者,以及近3月内服用过维生素D补充剂的儿童青少年,共选取7~18岁对象2 167名.采集研究对象空腹静脉血,采用酶联免疫吸附法(ELISA法)测定其血清25(OH)D的浓度.结果 银川、吴忠两市儿童青少年血清25(OH)D浓度中位数为51.46 nmol/L,四分位数间距为61.46 nmol/L,维生素D充足、不足、缺乏检出率分别为51.9%,14.1%,34.0%.不足检出率以7岁最高,8~13岁随着年龄的增长呈升高趋势,至14岁开始逐渐降低.7~18岁各年龄组儿童青少年缺乏检出率依次为31.9%,27.9%,20.8%,30.1%,36.7%,2.4%,29.8%,32.3%,35.3%,47.5%,37.3%,32.8%,各年龄组均较高.不同年龄组间维生素D水平及缺乏检出率比较,差异均有统计学意义(H=43.086,P<0.01;x2=11.156,P=0.001).回、汉族儿童青少年维生素D水平、不足与缺乏检出率比较,差异均无统计学意义(P值均>0.05).结论 银川、吴忠两市7~18岁儿童青少年维生素D水平较低,维生素D缺乏检出率较高;随年龄增长,儿童青少年血清维生素D水平逐渐降低,不足、缺乏检出率升高.     

Vitamin D: an overview of its role in skeletal muscle physiology in children and adolescents

Many children may have insufficient serum concentrations of vitamin D, which could prevent optimal muscle development and function. Vitamin D deficiency in animal models results in negative effects on muscle fiber structure and calcium/phosphorus handling, suggesting an integral role of vitamin D in skeletal muscle function. While there is a dearth of data in humans, the available evidence demonstrates a positive association between vitamin D status and muscle function. This review focuses on the important role of vitamin D in muscle function in children and adolescents who live in North American regions where exposure to ultraviolet B radiation is limited and who are thus at increased risk for vitamin D insufficiency. The effects of vitamin D on muscle cell proliferation and differentiation, muscle fiber structure, and calcium and phosphorus handling are discussed. Moreover, the roles of vitamin D and the vitamin D receptor and their genomic and nongenomic actions in muscle function are explored in depth. Future research should aim to establish a vitamin D status consistent with optimal musculoskeletal development and function in young children.     

Nutritional rickets: an old disease returns

Nutritional rickets, an ancient disease that was thought to have been cured in the early part of the 20th century, has made an unexpected comeback in recent years throughout the world. Although the frequency of its occurrence is poorly documented, increasing case reports of rickets are apparently related to low dietary intake of vitamin D and calcium and decreased sunshine exposure. Greater awareness of this problem is needed, as are further data regarding vitamin D status and incidence of rickets among infants and toddlers. Routine provision of supplemental vitamin D to all breastfed infants remains controversial, but may become more widely recommended.     

北京市区小儿佝偻病危险因素的研究

为了调查北京市区小儿这一特定人群佝偻病的危险因素,为综合防治小儿佝偻病、科学育儿提供理论依据。本文对经过综合诊断挑选的300名两岁以下婴幼儿做了集团性病例对照的研究。结果表明,母亲妊娠时维生素D(VD)的营养状况、出生情况、阳光照射程度、喂养情况均与小儿佝偻病的发病有关,提示预防小儿佝偻病应提倡“系统管理、早期防治、因地制宜、综合防治”的方针。     

Vitamin D Deficiency in India: Prevalence,Causalities and Interventions

Vitamin D deficiency prevails in epidemic proportions all over the Indian subcontinent, with a prevalence of 70%–100% in the general population. In India, widely consumed food items such as dairy products are rarely fortified with vitamin D. Indian socioreligious and cultural practices do not facilitate adequate sun exposure, thereby negating potential benefits of plentiful sunshine. Consequently, subclinical vitamin D deficiency is highly prevalent in both urban and rural settings, and across all socioeconomic and geographic strata. Vitamin D deficiency is likely to play an important role in the very high prevalence of rickets, osteoporosis, cardiovascular diseases, diabetes, cancer and infections such as tuberculosis in India. Fortification of staple foods with vitamin D is the most viable population based strategy to achieve vitamin D sufficiency. Unfortunately, even in advanced countries like USA and Canada, food fortification strategies with vitamin D have been only partially effective and have largely failed to attain vitamin D sufficiency. This article reviews the status of vitamin D nutrition in the Indian subcontinent and also the underlying causes for this epidemic. Implementation of population based educational and interventional strategies to combat this scourge require recognition of vitamin D deficiency as a public health problem by the governing bodies so that healthcare funds can be allocated appropriately.