Serum 25(OH)D response to vitamin D3 supplementation: A meta-regression analysis

ObjectiveThe aim of this study was to review factors that influence serum 25(OH)D when patients are given vitamin D supplements.MethodsFrom a comprehensive search of all randomized controlled clinical trials with vitamin D₃ supplementation available on PubMed up to November 2011, we selected 33 with 43 treatment arms that included at least 30 adult participants. The achieved pooled mean difference (PMD) and 95% confidence intervals (CIs) were calculated using the random-effects models. Meta-regression and subgroup analyses were performed for prespecified factors, including dose, duration, baseline serum 25(OH)D, and age.ResultsWith a mean baseline serum 25(OH)D of 50.4 nmol/L, PMD was 37 nmol/L (95% CI, 33–41) with significant heterogeneity among studies. Dose (slope: 0.006; P < 0.001), trial duration (slope: 0.21; P < 0.001), baseline serum 25(OH)D (slope: −0.19; P < 0.001), and age (slope: 0.42; P < 0.001) independently influenced vitamin D response. Similar results were found in studies with a mean baseline serum 25(OH)D <50 nmol/L. In subgroup analyses, the PMD was higher with doses ≥800 IU/d (39.3 nmol/L) after 6 to 12 mo (41.7 nmol/L), with baseline 25(OH)D <50 nmol/L (39.6 nmol/L), and in adults aged >80 y (40.5 nmol/L).ConclusionThis meta regression indicates that a higher increase in serum levels of 25(OH)D in adults is found with a dose of ≥800 IU/d, after at least 6 to 12 mo, and even when baseline 25(OH)D is low and in adults >80 y.     

High prevalence of vitamin D deficiency among children aged 1 month to 16 years in Hangzhou,China

Background

Recent studies have suggested that vitamin D deficiency in children is widespread. But the vitamin D status of Chinese children is seldom investigated. The objective of the present study was to survey the serum levels of 25-hydroxyvitamin D [25(OH)D] in more than 6,000 children aged 1 month to 16 years in Hangzhou (latitude: 30°N), the capital of Zhejiang Province, southeast China.

Methods

The children aged 1 month to 16 years who came to the child health care department of our hospital, the children's hospital affiliated to Zhejiang university school of medicine, for health examination were taken blood for 25(OH) D measurement. Serum 25(OH) D levels were determined by direct enzyme-linked immunosorbent assay and categorized as < 25, < 50, and < 75 nmol/L.

Results

A total of 6,008 children aged 1 month to 16 years participated in this cross-sectional study. All the subjects were divided into subgroups according to their age: 0-1y, 2-5y, 6-11y and 12-16y representing infancy, preschool, school age and adolescence stages respectively. The highest mean level of serum 25(OH)D was found in the 0-1y stage (99 nmol/L) and the lowest one was found in 12-16y stage (52 nmol/L). Accordingly, the prevalence of serum 25(OH)D levels of < 75 nmol/L and < 50 nmol/L were at the lowest among infants (33.6% and 5.4% respectively) and rose to the highest among adolescents (89.6% and 46.4% respectively). The mean levels of serum 25(OH)D and the prevalence of vitamin D deficiency changed according to seasons. In winter and spring, more than 50% of school age children and adolescents had a 25(OH)D level at < 50 nmol/L. If the threshold is changed to < 75 nmol/L, all of the adolescents (100%) had low 25(OH)D levels in winter and 93.7% school age children as well.

Conclusions

The prevalence of vitamin D deficiency and insufficiency among children in Hangzhou Zhejiang province is high, especially among children aged 6-16 years. We suggest that the recommendation for vitamin D supplementation in Chinese children should be extended to adolescence.

     

Vitamin D Deficiency and Its Association with Iron Deficiency in African Children

Vitamin D regulates the master iron hormone hepcidin, and iron in turn alters vitamin D metabolism. Although vitamin D and iron deficiency are highly prevalent globally, little is known about their interactions in Africa. To evaluate associations between vitamin D and iron status we measured markers of iron status, inflammation, malaria parasitemia, and 25-hydroxyvitamin D (25(OH)D) concentrations in 4509 children aged 0.3 months to 8 years living in Kenya, Uganda, Burkina Faso, The Gambia, and South Africa. Prevalence of iron deficiency was 35.1%, and prevalence of vitamin D deficiency was 0.6% and 7.8% as defined by 25(OH)D concentrations of <30 nmol/L and <50 nmol/L, respectively. Children with 25(OH)D concentrations of <50 nmol/L had a 98% increased risk of iron deficiency (OR 1.98 [95% CI 1.52, 2.58]) compared to those with 25(OH)D concentrations >75 nmol/L. 25(OH)D concentrations variably influenced individual markers of iron status. Inflammation interacted with 25(OH)D concentrations to predict ferritin levels. The link between vitamin D and iron status should be considered in strategies to manage these nutrient deficiencies in African children.     

Higher prevalence of vitamin D deficiency is associated with immigrant background among children and adolescents in Germany

In recent years, a high prevalence of vitamin D deficiency among children and adolescents has been reported in countries with moderate climates. Those with an immigrant background living under these conditions are at especially high risk. To date, representative data in Germany is lacking. We analyzed 25-hydroxyvitamin D [25(OH)D] concentrations of 10,015 children and adolescents, aged 1-17 y, who participated in the German National Health Interview and Examination Survey for Children and Adolescents. The proportion of immigrants was 25.4%, corresponding well to their percentage of the population. Among 3- to 17-y-old participants, 29% of immigrant boys and 31% of immigrant girls had 25(OH)D concentrations <25 nmol/L (severe to moderate vitamin D deficiency) compared with 18% of nonimmigrant boys and 17% of nonimmigrant girls. Furthermore, 92% of immigrant boys and 94% of immigrant girls had 25(OH)D concentrations <75 nmol/L (levels above 75 nmol/L are defined as optimal regarding various health outcomes) compared with 87% of nonimmigrants. Boys with a Turkish or Arab-Islamic background had an increased risk of having 25(OH)D concentrations <25 nmol/L compared with nonimmigrants (odds ratio [OR] 2.3; [95% CI] 1.4-3.8 and OR 7.6; [95% CI] 3.0-19.1). The same was true for girls with a Turkish (OR 5.2; [95% CI] 2.9-9.6), Arab-Islamic (OR 5.9; [95% CI] 2.5-14.0), Asian (OR 6.7; [95% CI] 2.2-19.8), or African (OR 7.8; [95% CI] 1.5-40.8) background. Supplementation of vitamin D beyond infancy, especially in high-risk groups, or fortification of food should be considered.     

Effects of vitamin D fortified milk on vitamin D status in Mongolian school age children

Mongolians are at high risk for vitamin D deficiency because of their residence at northern latitude, reduced exposure to UV-B rays during the winter months, and a low availability of vitamin-D fortified foods. We performed a pilot study in May 2005 to estimate the prevalence of hypovitaminosis D in Mongolian school age children and to determine the feasibility of conducting a longer and larger trial with fortified milk and vitamin D supplements. In a group of 46 Mongolian children (22 girls and 24 boys) aged 9-11 years, 76% (35) had levels of 25-hydroxyvitamin D (25(OH)D) below 50 nmol/L (20 ng/mL) and 32% had levels below 37 nmol/L (15 ng/mL). After a month of consuming 710 ml of vitamin D-fortified (total 300 IU or 7.5 microg) milk daily, only 3 of the children were below 50 nmol/L (20 ng/mL) and none below 37 nmol/L (15 ng/mL). These results reveal prevalent and serious 25(OH)D deficiency among Mongolian prepubertal school age children that appears to be ameliorated by a month of consuming approximately 7.5 microg of vitamin D3 in fortified milk.     

Low wintertime vitamin D levels in a sample of healthy young adults of diverse ancestry living in the Toronto area: associations with vitamin D intake and skin pigmentation

Background  

Vitamin D plays a critical role in bone metabolism and many cellular and immunological processes. Recent research indicates that concentrations of serum 25-hydroxyvitamin D [25(OH)D], the main indicator of vitamin D status, should be in excess of 75 nmol/L. Low levels of 25(OH)D have been associated with several chronic and infectious diseases. Previous studies have reported that many otherwise healthy adults of European ancestry living in Canada have low vitamin D concentrations during the wintertime. However, those of non-European ancestry are at a higher risk of having low vitamin D levels. The main goal of this study was to examine the vitamin D status and vitamin D intake of young Canadian adults of diverse ancestry during the winter months.     

Serum 25-hydroxyvitamin D levels among Mexican children ages 2 y to 12 y: A national survey

ObjectiveThe aim of this study was to assess the vitamin D status in preschool and school-age children in Mexico.Methods25-hydroxyvitamin D (25-OH-D) serum concentrations were measured using a direct enzyme-linked immunosorbent assay commercial kit in a nationally representative sample of 1025 Mexican children ages 2 y to 12 y who participated in the 2006 Mexican National Health and Nutrition Survey.ResultsMean serum 25-OH-D concentration was 94.6 ± 47 nmol/L. Concentrations were lower in preschool children (2–5 y; 78.3 ± 37 nmol/L) than in school-aged children (6–12 y; 105.8 ± 51 nmol/L; P < 0.001). Children living in urban areas had lower levels (89.8 ± 36 nmol/L) than children from rural areas (108.1 ± 75 nmol/L; P < 0.05). Twenty-four percent of preschool children had vitamin D deficiency (25-OH-D < 50 nmol/L) compared with 10% of school-aged children (P < 0.05). Thirty percent of preschool children had vitamin D insufficiency (25-OH-D 50–74.9 nmol/L) compared with 18% of school-aged children (P < 0.05). In urban areas, 18% of children had vitamin D deficiency and 25% had insufficiency compared with 10% and 16% of children in rural areas, respectively (P < 0.05). Prevalence of severe vitamin D deficiency (25-OH-D < 20 nmol/L) was extremely low (0.3%).ConclusionsVitamin D deficiency and insufficiency are important public health problems in Mexican children.     

Association of modifiable and nonmodifiable factors with vitamin D status in pregnant women and neonates in Oakland, CA

There is little information on the contribution of modifiable vs nonmodifiable factors to maternal and neonatal vitamin D status in temperate regions of the United States. The purpose of this cross-sectional observation study conducted between December 2006 and February 2008 was to identify associations between observed and measured maternal characteristics and vitamin D status at term in pregnant women and their infants in a multiethnic community in Oakland, CA. Two hundred seventy-five pregnant women aged 18 to 45 years and carrying a singleton fetus were recruited and data from 210 mother-infant pairs were included in analyses. Analysis of covariance identified predictors of maternal and cord serum 25-hydroxyvitamin D [25(OH)D] in a multivariate model considering vitamin D intake, lifestyle factors, and skin pigmentation. Maternal serum 25(OH)D was significantly associated with season of delivery (P=0.0002), average daily D intake (P=0.0008), right upper inner arm pigmentation (P=0.0035), and maternal pre- or early-pregnancy body mass index (calculated as kg/m²) (P=0.0207). The same factors were significant for cord serum 25(OH)D, which was highly correlated with maternal serum 25(OH)D (r=0.79; P<0.0001). During the year, 54% of mothers and 90% of neonates had 25(OH)D <30 ng/mL (<75 nmol/L). Of women taking daily prenatal vitamin/mineral supplements (400 IU vitamin D), 50.7% had serum 25(OH)D <30 ng/mL (<75 nmol/L). In conclusion, 25(OH)D <30 ng/mL (<75 nmol/L) was prevalent in mothers and neonates across racial groups and seasons, and vitamin D status was associated with both modifiable and nonmodifiable risk factors.     

Mismatch: a comparative study of vitamin D status in British-Bangladeshi migrants

Background and objectivesLow levels of vitamin D among dark-skinned migrants to northern latitudes and increased risks for associated pathologies illustrate an evolutionary mismatch between an environment of high ultraviolet (UV) radiation to which such migrants are adapted and the low UV environment to which they migrate. Recently, low levels of vitamin D have also been associated with higher risks for contracting COVID-19. South Asians in the UK have higher risk for low vitamin D levels. In this study, we assessed vitamin D status of British-Bangladeshi migrants compared with white British residents and Bangladeshis still living in Bangladesh (‘sedentees’).MethodologyThe cross-sectional study compared serum vitamin D levels among 149 women aged 35–59, comprising British-Bangladeshi migrants (n = 50), white British neighbors (n = 54) and Bangladeshi sedentees (n = 45). Analyses comprised multivariate models to assess serum levels of 25-hydroxyvitamin D (25(OH)D), and associations with anthropometric, lifestyle, health and migration factors.ResultsVitamin D levels in Bangladeshi migrants were very low: mean 25(OH)D = 32.2 nmol/L ± 13.0, with 29% of migrants classified as deficient (<25 nmol/L) and 94% deficient or insufficient (≤50 nmol/L). Mean levels of vitamin D were significantly lower among British-Bangladeshis compared with Bangladeshi sedentees (50.9 nmol/L ± 13.3, P < 0.001) and were also lower than in white British women (55.3 nmol/L ± 20.9). Lower levels of vitamin D were associated with increased body mass index and low iron status.Conclusions and implicationsWe conclude that lower exposure to sunlight in the UK reduces vitamin D levels in Bangladeshi migrants. Recommending supplements could prevent potentially adverse health outcomes associated with vitamin D deficiency.Lay SummaryVitamin D deficiency is one example of mismatch between an evolved trait and novel environments. Here we compare vitamin D status of dark-skinned British-Bangladeshi migrants in the UK to Bangladeshis in Bangladesh and white British individuals. Migrants had lower levels of vitamin D and are at risk for associated pathologies.     

Moderate Amounts of Vitamin D3 in Supplements are Effective in Raising Serum 25-Hydroxyvitamin D from Low Baseline Levels in Adults: A Systematic Review

There is controversy surrounding the designation of vitamin D adequacy as defined by circulating levels of the metabolite 25-hydroxyvitamin D (25(OH)D). Depending on the cutoff level chosen, dietary intakes of vitamin D may or may not provide sufficient impact upon vitamin D status measured as improvement in serum levels of 25(OH)D. We sought to examine whether modest daily doses (5–20 μg) as found in fortified foods or multivitamin supplements had a measureable impact on vitamin D status, defined as moving from below to above 50 nmol/L, or from less than 30 nmol/L to above 30 nmol/L. Published literature was searched for relevant articles describing randomized controlled trials. Exclusion criteria were: studies not involving humans; review articles; studies lacking blood level data pre- and post-treatment; no control group; bolus treatments (weekly, monthly, yearly); vitamin D <5 μg or >20 μg; baseline 25(OH)D ≥75 nmol/L; subjects not defined as healthy; studies <8 weeks; and age <19 years. Of the 127 studies retrieved, 18 publications with 25 separate comparisons met criteria. The mean rate constant, defined as change in 25(OH)D in nmol/L per μg vitamin D administered, was calculated as 2.19 ± 0.97 nmol/L per μg. There was a significant negative correlation (r = −0.65, p = 0.0004) between rate constant and administered dose. To determine impact of the dose reflecting the Estimated Average Requirement (EAR) of 10 μg administered in nine studies (10 comparisons), in every case mean 25(OH)D status rose either from “insufficient” (30–50 nmol/L) to “sufficient” (>50 nmol/L) or from “deficient” (<30 nmol/L) to “insufficient” (>30 but <50 nmol/L). Our study shows that when baseline levels of groups were <75 nmol/L, for every microgram of vitamin D provided, 25(OH)D levels can be raised by 2 nmol/L; and further, when groups were deficient or insufficient in vitamin D, there was significant value in providing additional 10 μg per day of vitamin D.     

学龄儿童维生素D营养状况与身体肌肉量关系的研究

目的探讨学龄儿童维生素D营养状况与身体肌肉量的关系。方法研究对象来自“儿童青少年心血管与骨健康促进项目”,于2017年采用分层整群抽样的方法在北京市对15391名6~16岁儿童开展基线调查,2019年对其进行随访调查。进行问卷调查和检测血清25(OH)D,使用生物电阻抗法测定机体肌肉量,并计算全身肌肉质量指数(MMI)。采用多因素线性回归分析维生素D营养状况与基线和随访期MMI的关系。结果纳入分析的10890名儿童的年龄为(11.5±3.3)岁,男童占49.6%,基线25(OH)D水平为(35.4±12.0)nmol/L,充足率为11.1%。多因素线性回归校正年龄、性别、体脂肪量、吸烟、饮酒、奶制品摄入、维生素D补充、钙剂补充、体力活动、青春期发育状态后,未观察到维生素D营养状况与基线MMI水平关联有统计学意义(P>0.05)。而对于随访时点MMI,25(OH)D每增加10 nmol/L,其Z值增加0.008(P=0.058);相比于维生素D缺乏,维生素D不足和充足的儿童分别增高0.002(P=0.815)和0.037(P=0.031),趋势P=0.089。亚组分析显示,在BMI正常组中,25(OH)D每增加10 nmol/L,维生素D充足的儿童基线MMI和随访时点MMI Z值分别增高0.019和0.014,均P<0.05。结论儿童维生素D营养状况与身体肌肉量有关,维生素D充足的儿童倾向于在未来获得更高的肌肉量。倡导儿童青少年维持充足的维生素D水平,加强营养与运动,提升身体素质。     

2012年广州地区25 295名儿童维生素D营养状况分析

目的 分析广州地区25 295名儿童维生素D营养状况与年龄、季节的关系。 方法 采用酶联免疫法检测25-羟基维生素D[25-(OH)D]水平,收集2012年全年广州市妇女儿童医疗中心25 295例0~16周岁健康儿童25-(OH)D结果,维生素D营养状况以血清水平判断:维生素D严重缺乏(<12.5 nmol/L)、维生素D缺乏(12.5~37.5 nmol/L)、维生素D不足(37.5~50.0 nmol/L),分别各年龄组及各月份应用SPSS 17.0统计软件进行分析。结果 2012年广州地区25 295例儿童25-(OH)D平均水平72.41 nmol/L,无性别差异;无维生素D严重缺乏病例;25-(OH)D<50 nmol/L的比例为13.22%。儿童25-(OH)D水平随年龄的增长而降低,维生素D的缺乏和不足与年龄呈正比;2012年1月份为全年最低水平,1~7月份25-(OH)D水平逐月上升, 8、9月份达到全年峰值,10~12月份逐月下降;各月份维生素D缺乏和不足的比例在1月份为全年最高,全年最低值在9月份。 结论广州地区在冬春季节儿童维生素D营养水平较低,3周岁以上的儿童维生素D营养缺乏较严重。     

Vitamin D Intake and Status in 12-Month-Old Infants at 63–66° N

The objective was to assess the vitamin D status in healthy 12-month-old infants in relation to quantity and sources of dietary vitamin D, breastfeeding and seasons. Subjects were 76 12-month-old infants. Serum levels of 25-hydroxyvitamin D (25(OH)D) ≥ 50 nmol/L were considered indicative of vitamin D sufficiency and 25(OH)D < 27.5 nmol/L as being indicative of increased risk for rickets. Additionally, 25(OH)D > 125 nmol/L was considered possibly adversely high. Total vitamin D at 9–12 months (eight data collection days) included intake from diet and supplements. The mean ± SD of vitamin D intake was 8.8 ± 5.2 μg/day and serum 25(OH)D 98.1 ± 32.2 nmol/L (range 39.3–165.5). Ninety-two percent of infants were vitamin D sufficient and none at increased risk for rickets. The 26% infants using fortified products and supplements never/irregularly or in small amounts had lower 25(OH)D (76.8 ± 27.1 nmol/L) than the 22% using fortified products (100.0 ± 31.4 nmol/L), 18% using supplements (104.6 ± 37.0 nmol/L) and 33% using both (110.3 ± 26.6 nmol/L). Five of six infants with 25(OH)D < 50 nmol/L had no intake of supplements or fortified products from 0 to 12 months. Supplement use increased the odds of 25(OH)D > 125 nmol/L. Breastfeeding and season did not affect vitamin D status. The majority of infants were vitamin D sufficient. Our findings highlight the need for vitamin D supplements or fortified products all year round, regardless of breastfeeding.     

Associations between Body Composition and Vitamin D Status in Children with Overweight and Obesity Participating in a 1-Year Lifestyle Intervention

Background: To examine associations between body composition and vitamin D status in children participating in a lifestyle intervention. Methods: Children (6–12 y, n = 101) with a body mass index (BMI)-for-age >85th percentile were randomized to six dietitian-led behavior counselling sessions or no intervention. Plasma 25-hydroxyvitamin D (25(OH)D), anthropometry, and body composition using dual-energy X-ray absorptiometry were assessed every 3 months for 1 year. For each anthropometry variable (z-scores), tertiles were created to test for differences in 25(OH)D over time (tertile-by-time), and for changes in the z-score (loss, maintain, gain)-by-time, and according to fat patterning (android vs. gynoid) using mixed effects models. Results: The baseline plasma 25(OH)D was 62.2 nmol/L (95%CI: 58.7–65.7), and none < 30 nmol/L. At 6 mo, children with gynoid fat patterning had higher 25(OH)D concentrations than in those with android fat patterning (64.5 ± 1.1 nmol/L vs. 50.4 ± 1.0 nmol/L, p < 0.003, Cohen’s f = 0.20). Children with the lowest lean mass index z-score at 9 mo had higher plasma 25(OH)D concentrations than children with the highest z-score at baseline, 3 mo, and 6 mo (p < 0.05, Cohen’s f = 0.20). No other significant differences were observed. Conclusion: In this longitudinal study, vitamin D deficiency was not present in children 6–12 y of age with obesity. Reductions in adiposity did not alter the vitamin D status.     

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.     

Plasma 25-hydroxyvitamin D is positively associated with folate and vitamin B12 levels in adolescents

Vitamin D affects the absorption of folate in vitro, and perhaps of vitamin B₁₂ (B₁₂). However, epidemiological studies on the association of vitamin D with folate and B₁₂ are inconclusive. We hypothesized a positive association of plasma 25-hydroxyvitamin D [25(OH)D] with folate and B₁₂ levels in adolescents. This hypothesis was tested in a cross-sectional study of healthy adolescents (11–16 years old; n = 1416), selected from public middle schools from across Kuwait, using stratified multistage cluster random sampling. Plasma 25(OH)D was measured by LC–MS/MS. Serum B₁₂ and total folate in hemolyzed whole blood were analyzed with commercial kits; RBC and plasma folate were calculated from total folate. Data on potential confounders were collected from the parents and adolescents. In a univariable model, 25(OH)D as a continuous variable was positively associated with each of total, RBC, and plasma folate (P < .001). After adjusting for potential confounders, this association remained significant with total folate (β = 2.0, P < .001) and red blood cell folate (β = 1.8, P < .001), but not with plasma folate (β = 0.2, P = .34). A similar pattern of association was evident when 25(OH)D was fitted as categorical variable. Correlation between B₁₂ and 25(OH)D was weak but significant (ρ = 0.1, P < .001). 25(OH)D was positively associated with B₁₂ in both univariable and multivariable models (P < .001) when fitted as a categorical variable only. Simultaneous quantile regression confirmed these results. We conclude that plasma 25(OH)D is positively associated with folate and B₁₂ levels in adolescents. Properly designed large-scale randomized controlled trials are warranted to investigate the causal role of vitamin D in folate and B₁₂ absorption.     

血浆25-羟维生素D水平和儿童中枢性性早熟相关性研究

目的 了解中枢性性早熟(CPP)组儿童25-羟维生素D[25(OH)D]水平和区间分布,分析CPP儿童性激素与25(OH)D水平的相关性。方法 以2015年本院内分泌科确诊的182例CPP患儿为研究对象,选择同期在儿童保健科健康体检的同年龄段儿童200例为对照组,采用电化学分析检测血浆25(OH)D水平,并将25(OH)D水平与黄体生成素(LH)/卵泡刺激素(FSH)峰值比进行相关分析。结果 CPP组儿童25(OH)D水平比对照组低[(55.7±16.9)nmol/L vs.(66.5±20.1)nmol/L], 差异有统计学意义(t=5.70, P<0.05),25(OH)D水平与LH/FSH峰值比存在负相关关系(r=-0.74,P<0.05);两组25(OH)D水平构成不同,维生素D缺乏区间CPP占比(39.7%)高于对照组(22.2%),维生素D充足区间CPP占比(16.3%)低于对照组(33.3%)。结论 CPP儿童青春期提前骨骼生长发育快,维生素D需求量大,在儿童性早熟的治疗过程中应加强对维生素D重视,定期监测25(OH)D水平,补充维生素D。     

Vitamin D status and recommendations to improve vitamin D status in Canadian youth

Little is known regarding the vitamin D status of Canadian youth. Our objectives were (i) to describe the vitamin D status of Quebec youth using a representative sample; (ii) to examine the relative contributions of diet, physical activity, and fat mass to the variance in plasma 25-hydroxyvitamin D(25(OH)D), the best biomarker of vitamin D status; and (iii) to examine the influence of household income and food insecurity on the intakes of dietary vitamin D, calcium, and dairy foods. To describe vitamin D status, we used data from the Quebec Child and Adolescent Health and Social Survey (QCAHS), which is a cross-sectional survey representative of Quebec youth aged 9, 13, and 16 years. For the second objective, 159 youth, aged 8 to 11 years, whose parents (at least one) were obese or had the metabolic syndrome, were used for cross-sectional analysis in the Quebec Adipose and Lifestyle InvesTigation in Youth (QUALITY). Fat mass was measured using dual X-ray absorptiometry (DXA), and physical activity was assessed by an accelerometer. Finally, we analyzed data from the Canadian Community Health Survey (CCHS), which collected data from 9 to 18 year olds (N = 8960), and was representative of Canadian youth. From this survey a single 24-h dietary recall, measured height and weight, sociodemographic, and food insecurity information were available. In both the QUALITY and QCAHS study, >90% of youth had suboptimal vitamin D levels (plasma 25(OH)D < 75 nmol L(-1)) at the end of winter and beginning of spring. In the QCAHS study, older youth had a higher prevalence of vitamin D deficiency (25(OH)D < 27.5 nmol L(-1)) (>10%) than younger youth, and girls from low-income households had lower plasma 25(OH)D concentrations. In the QUALITY study, milk consumption and physical activity had modest associations with plasma 25(OH)D, corresponding to 2.9 nmol L(-1) and 2.1 nmol L(-1) higher plasma 25(OH)D per standard deviation increase in these exposures, respectively. In the CCHS study, we found evidence that milk intake was being displaced by sweetened beverages among low-income boys and food insecure girls. We conclude that population-wide measures to increase dietary vitamin D intake should be examined in Canadian youth.     

Optimal vitamin D status and serum parathyroid hormone concentrations in African American women

BACKGROUND: Optimal vitamin D status for the prevention of osteoporosis has been inferred from examinations of the serum 25-hydroxyvitamin D [25(OH)D] concentration below which there is an increase in serum parathyroid hormone (PTH). OBJECTIVE: The objectives of the study were to ascertain whether a threshold for serum 25(OH)D exists below which serum PTH increases and whether persons with 25(OH)D above this threshold have lower rates of bone loss than do persons with 25(OH)D below the threshold. DESIGN: The relation of serum 25(OH)D to serum PTH was analyzed in 208 African American women studied longitudinally for 3 y. These healthy women in midlife were randomly assigned to receive placebo or 800 IU vitamin D3/d; after 2 y, the vitamin D3 supplementation was increased to 2000 IU/d. Both groups received calcium supplements to ensure an adequate calcium intake. A systematic literature review found a wide range of threshold values in part due to varied calcium intake. RESULTS: A Loess plot suggested a breakpoint between 40 and 50 nmol/L for serum 25(OH)D. A line-line model was fitted to the data, and it showed a spline knot at 44 nmol/L. A heuristic approach verified that PTH does not decline as rapidly when the serum concentration of 25(OH)D is >40 nmol/L as when it is <40 nmol/L. We found no significant difference in rates of bone loss between persons with 25(OH)D concentrations above and below 40 nmol/L. CONCLUSION: Although a threshold for 25(OH)D can be identified, we suggest that it should not be used to recommend optimal vitamin D status.     

The routine chemiluminescence assay for plasma 25-hydroxyvitamin D analysis does not overestimate the prevalence of vitamin D deficiency in adolescents

Vitamin D deficiency (VDD) is a global public health problem. Inaccurate methods for measuring plasma 25-hydroxyvitamin D (25[OH]D) may have contributed to the reported high prevalence of VDD. We hypothesized that the most commonly used assay for vitamin D status, chemiluminescence immunoassay (CLIA), underestimates 25(OH)D levels and thus overestimates VDD. Using both liquid chromatography–tandem mass spectrometry and CLIA for plasma 25(OH)D, we evaluated the prevalence of VDD in adolescents (11-16 years-old; n = 410) by both methods in a cross-sectional study. Subjects were selected from public middle schools from all the 6 Governorates of Kuwait using stratified multistage cluster random sampling. Cohen κ agreement, linear regression, and Bland-Altman plots were used to evaluate the classification of VDD by the 2 methods. VDD (25[OH]D < 50 nmol/L) was 85.9% with CLIA and 81.2% with liquid chromatography–tandem mass spectrometry. There was a good agreement between the 2 methods in classifying the study subjects as deficient, insufficient, or sufficient (κ = 85.1%, P < .001). The between-assay bias was very small with a mean percentage difference < 1% from the mean value of the 25(OH)D as assessed by the 2 methods. These data did not support our hypothesis, and we conclude that the routine methods used for plasma 25(OH)D levels have no or little impact on evaluating VDD as a public health problem or in clinical management.