High prevalence of vitamin D deficiency in school-age children in Tehran, 2008: a red alert. Public Health Nutr. 2012;15:324-330. [PMID: 21356149 DOI: 10.1017/s1368980011000188]

Relationship between 25-Hydroxy Vitamin-D and Obesity in 2-7 years old Children Referred to a Paediatric Hospital in Iran

BACKGROUND

Obesity is increasing in children and it can cause many complications in adulthood, such as Diabetes mellitus (DM) and metabolic syndrome. In observational studies, vitamin-D was one of the factors which were found to be associated with obesity.

AIMS

To determine the association between body mass index (BMI) and serum level of vitamin-D in children who were outpatients at Taleghani Paediatric Hospital, Iran.

SETTINGS AND DESIGN

This was a cross-sectional observational study done on 215 children who were 2 to 7 y old, who were referred to Taleghani Hospital in winter (1391 solar calendar) 2013.

MATERIALS AND METHODS

In this cross-sectional study, anthropometric indices: weight, height and waist circumference were measured by using identical instruments. BMI was also determined as per CDC 2000 criteria. Vitamin-D levels were estimated by ELISA.

STATISTICAL ANALYSIS

Vitamin-D levels which were less than 20 nmol/L were considered as a deficiency, levels which were 20-30 nmol\L were considered as inadequate and those which were equal to or greater than 30 nmol\L were considered as sufficient. t-test, ANOVA and Pearson's correlation coefficient at a significant level of 0.05 were applied and data were analysed by using SPSS (version 16).

RESULTS

One hundred and twenty five children (47.4%) were males and the rest were females. One hundred eighty four children (85.6%) had vitamin-D deficiency and only 31 had adequate levels of vitamin-D. The prevalence of obesity and overweight were 27%, but considering the vitamin-D status, it was found to be insignificant. However, there was a linear relationship between waist circumference and serum vitamin-D (p<0.01). The means and standard deviations of serum vitamin-D levels in girls and boys were 22.76 ±11.62 and 23.46 ± 9.30 nmol/L and this difference was not significant. Vitamin-D levels found in the three ethnic groups of Fars, Turkmen and Sistani showed significant differences (p<0.002).

CONCLUSIONS

There was a high prevalence of vitamin-D deficiency in 2 to 7 year olds. There was no significant relationship between BMI and vitamin-D, but it was recorded in ethnic groups, and there was a correlation between waist circumference and vitamin-D levels. More exposure to sunlight and prescription of vitamin supplements were recommended.

Vitamin D status among Thai school children and the association with 1,25-Dihydroxyvitamin D and parathyroid hormone levels

In several low latitude countries, vitamin D deficiency is emerging as a public health issue. Adequate vitamin D is essential for bone health in rapidly growing children. In the Thai population, little is known about serum 25-hydroxyvitamin D [25(OH)D] status of infants and children. Moreover, the association between 25(OH)D and the biological active form of 1,25-dihydroxyvitamin D [1,25(OH)]₂D is not clear. The specific aims of this study were to characterize circulating serum 25(OH)D, 1,25(OH)₂D and their determinants including parathyroid hormone (PTH), age, sex, height and body mass index (BMI) in 529 school-aged Thai children aged 6–14 y. Adjusted linear regression analysis was performed to examine the impact of age and BMI, and its interaction with sex, on serum 25(OH)D concentrations and 1,25(OH)₂D concentrations. Serum 25(OH)D, 1,25(OH)₂D and PTH concentrations (geometric mean ± geometric SD) were 72.7±1.2 nmol/L, 199.1±1.3 pmol/L and 35.0±1.5 ng/L, respectively. Only 4% (21 of 529) participants had a serum 25(OH)D level below 50 nmol/L. There was statistically significant evidence for an interaction between sex and age with regard to 25(OH)D concentrations. Specifically, 25(OH)D concentrations were 19% higher in males. Moreover, females experienced a statistically significant 4% decline in serum 25(OH)D levels for each increasing year of age (P = 0.001); no decline was seen in male participants with increasing age (P = 0.93). When BMI, age, sex, height and serum 25(OH)D were individually regressed on 1,25(OH)₂D, height and sex were associated with 1,25(OH)₂D with females exhibiting statistically significantly higher serum 1,25(OH)₂D levels compared with males (P<0.001). Serum 1,25(OH)₂D among our sample of children exhibiting fairly sufficient vitamin D status were higher than previous reports suggesting an adaptive mechanism to maximize calcium absorption.

National report on the association of serum vitamin D with cardiometabolic risk factors in the pediatric population of the Middle East and North Africa (MENA): the CASPIAN-III Study

OBJECTIVES

As the first, to our knowledge, nationwide study in the Middle East and North Africa (MENA), this study aimed to investigate the association of serum 25 hydroxy vitamin D [25(OH)D] levels with cardiometabolic risk factors in a nationally representative sample of the pediatric population in Iran. The second objective was to provide the prevalence of hypovitaminosis D and the percentiles of serum 25(OH)D in the study population.

METHODS

This national population-based study was conducted among 1100 Iranian students living in 27 provinces in Iran. The association of 25(OH)D with each cardiometabolic risk factor was determined after adjustment for age, gender, body mass index, and waist circumference.

RESULTS

Participants consisted of 1095 students (52% boys) with a mean age of 14.74 ± 2.61 y. The median 25(OH)D level corresponded to a vitamin D insufficiency level: 12.70 ng/mL in boys and 13.20 ng/mL in girls. Overall, 40% of participants were vitamin D deficient, and 39% had vitamin D insufficiency. There were no significant differences in these findings between boys and girls. Adjusted regression analysis revealed a significant weak inverse association of 25(OH)D with systolic blood pressure, diastolic blood pressure, total cholesterol, and low-density lipoprotein cholesterol. This association was significantly positive with high-density lipoprotein cholesterol, but not with fasting plasma glucose and metabolic syndrome.

CONCLUSION

We found a considerably high prevalence of hypovitaminosis D in the pediatric population of a sunny region. Our findings also revealed an association of hypovitaminosis D with many cardiometabolic risk factors from childhood; these associations were independent of obesity indexes. It is of special concern that the highly prevalent disorders of low 25(OH)D and low high-density lipoprotein cholesterol in children and adolescents of the MENA region had significant association. The clinical importance of our findings needs to be confirmed in longitudinal studies.

Prevalence of vitamin D deficiency among Iranian adolescents

OBJECTIVE

Despite the high prevalence of vitamin D deficiency in adults worldwide, not many studies have evaluated the condition in adolescents. The present study was therefore conducted to assess the prevalence of vitamin D deficiency in a group of students from Shahroud, Iran.

METHODS

The cross-sectional descriptive analytical study was conducted on junior high and high school students of both genders from urban and rural areas of Shahroud, the largest city of Semnan Province in Iran, in winter 2011. The combination of stratified and cluster random sampling methods was applied in the study. A questionnaire on the demographic data, socioeconomic status, lifestyle habits (sun exposure, physical activity, dairy consumption), and drug and personal history was completed for each student. Blood samples were taken to assess vitamin D levels.

RESULTS

One thousand forty-seven students from four junior high and six high schools were recruited. From among them, 42.2% were boys and 57.8% were girls. Mean and standard deviation of vitamin D levels in the studied population were 14.7 ± 9.4 ng/mL. Only 7.2% of the boys and 3.8% of the girls had sensible sun exposure. The median of milk consumption was 3 glasses per week, ranging from 0 to 7.

CONCLUSION

It could be concluded that vitamin D deficiency is quite prevalent among the Iranian adolescents, and this is mainly because this group follows an unhealthy lifestyle due to osteoporosis.

Hypovitaminosis D in a sunny country: time trends, predictors, and implications for practice guidelines

The aim of the current study is to investigate the prevalence of hypovitaminosis D in Lebanese subjects, its robust predictors, evaluate the relationship between 25 hydroxy vitamin D [25(OH)D] and parathyroid hormone levels, and derive desirable vitamin D levels, based on a large hospital laboratory database spanning all age groups. Data from a large representative digitized database of 9147 subjects, mostly outpatients, evaluated between 2000-2004 and 2007-2008, in whom information on age, gender, service, and time of the year, was analyzed. The PTH-25(OH)D relationship was studied in a subset of 657 adult subjects, in whom such data were available. At a 25(OH)D cut-off of<20 ng/ml, the prevalence of hypovitaminosis D ranged between 58% and 62% in pediatric subjects, 44% and 60% in adults, and 41% and 62% in elderly, in the 2 study periods. At a cut-off <30 ng/ml, the prevalence was above 78%, in most sub-groups. Regardless of cut-off used, the only significant predictors of high mean 25(OH)D levels were the male gender in the pediatric group, and female gender in adults and elderly, summer/fall seasons, out-patient status, as well as study period. Curve fitting of the PTH-25(OH)D relationship, in adults and elderly, revealed a plateau at 25(OH)D levels of 17-21 ng/ml, depending on sub-study group. Hypovitaminosis D is prevalent in our sunny country, even using a conservative population-derived cut-off of 20 ng/ml, and thus the need for a public health strategy for supplementation.

Prevalence of vitamin D deficiency and its related factors in children and adolescents living in North Khorasan, Iran

INTRODUCTION

Vitamin D deficiency is recognized as an epidemic among children. The present study has analyzed serum 25 hydroxyvitamin D [25(OH)D] levels of children living in the city of Bojnurd, located in the North Khorasan province of Iran.

METHODS

In this cross-sectional study, 361 subjects (175 boys and 186 girls) aged 7-18 years participated; 25(OH)D, parathyroid hormone (PTH), and anthropometric measurements were obtained. Deficiency, insufficiency and sufficiency of vitamin D was assessed based on the relationship between 25(OH)D and PTH. Vitamin D status was reported according to gender and age group of participants.

RESULTS

The prevalence of vitamin D deficiency was 16.1% and its insufficiency was 25.2%. Girls had higher levels of vitamin D deficiency (30.6%) and insufficiency (38.7%). The mean level of serum 25(OH)D decreased in older age groups. The age-adjusted odds of serum 25(OH)D <30 was 21.12 higher in girls compared to boys.

CONCLUSION

The prevalence of vitamin D deficiency and insufficiency was high. The ratio in girls was higher than in boys.

Vitamin D status and its relationship with metabolic syndrome risk factors among adolescent girls in Boukan, Iran

OBJECTIVE

To investigate vitamin D status and its association with components of the metabolic syndrome (MetS) in adolescent girls attending high school in Boukan, Iran during winter 2012.

DESIGN

A cross-sectional study.

SETTING

High schools of Boukan city, Iran.

SUBJECTS

A sample of 216 girls aged 14-17 years was selected by multistage random sampling from four districts of Boukan. Weight, height, waist circumference, blood pressure, daily energy intake, physical activity and serum 25-hydroxyvitamin D (25(OH)D), fasting blood glucose, TAG and HDL-cholesterol levels of all participants were evaluated. Serum 25(OH)D level <20 ng/ml was defined as vitamin D deficiency.

RESULTS

Mean serum 25(OH)D was 7.26 (sd 2.81) ng/ml and 96 % of the participants had vitamin D deficiency. According to age-modified definitions of the National Cholesterol Education Program Adult Treatment Panel III, MetS was diagnosed in 10.6% of the participants. In multivariable regression analysis after adjustment for BMI, energy intake and physical activity level, serum 25(OH)D was inversely associated with fasting blood glucose (β = -0.143, P = 0.04). No significant relationship was found between serum 25(OH)D and other components of MetS.

CONCLUSIONS

The high prevalence of vitamin D deficiency warrants national polices and interventions towards improving this major health problem among adolescent girls. Low 25(OH)D level was significantly associated with increased fasting blood glucose. Prospective studies are needed to determine the effects of vitamin D deficiency on the development of MetS and related metabolic diseases in adolescent girls.

Prevalence of 25-hydroxyvitamin D deficiency in Korean adolescents: association with age, season and parental vitamin D status

OBJECTIVE

We aimed to assess the prevalence and associated factors of vitamin D deficiency in healthy adolescents and to determine parent-adolescent association in vitamin D status.

DESIGN

A cross-sectional study.

SETTING

Data from the Korean National Health and Nutrition Examination Survey (KNHANES) 2008-2009. Serum 25-hydroxyvitamin D (25(OH)D) levels were measured using 125I-labelled RIA kits. Vitamin D deficiency in adolescents was defined as 25(OH)D level <27·5 nmol/l, and 25(OH)D levels between 27·5 and <50 nmol/l were considered insufficient. For the parents, vitamin D deficiency was defined as 25(OH)D level <50 nmol/l.

SUBJECTS

The study population consisted of 2062 adolescents (1095 boys, 967 girls; aged 10-18 years) and their parents (1005 fathers, 1341 mothers).

RESULTS

Overall, 13·4% of adolescents (boys 11·7%, girls 15·4%) were 25(OH)D deficient, 54·7% were 25(OH)D insufficient. Prevalence of vitamin D deficiency increased with age (P < 0·0001). Parental vitamin D deficiency was more prevalent in vitamin D-deficient adolescents than in non-deficient adolescents (all P < 0·0001). In multivariate logistic regression analyses, predictors for vitamin D deficiency were senior high school students (OR = 3·45-4·33), winter/spring season (OR = 3·18-5·11/5·35-7·36) and parental vitamin D deficiency (OR = 1·78-4·88; all P < 0·05).

CONCLUSIONS

Vitamin D insufficiency is prevalent among healthy Korean adolescents and the parent-offspring association warrants vitamin D screening for family members of deficient individuals.

Subclinical Vitamin D Insufficiency in Korean School-aged Children

PURPOSE

Recently, vitamin D insufficiency has increased and has been correlated to growth and puberty in children. This study was conducted to find the prevalence of subclinical vitamin D insufficiency and its influence on school-aged children in Korea.

METHODS

The subjects of this study were 397 children aged 7 to 15 years who had been tested for 25-OH vitamin D3 among the outpatients of the Department of Pediatrics in Eulji General Hospital from March 2007 to February 2011. Data for age, sex, comorbidities, serum 25-OH vitamin D3, height, weight, body mass index (BMI), and sunlight exposure time were collected before and after 3 months of vitamin D administration, retrospectively.

RESULTS

Vitamin D insufficiency was present in 343 (86%) of the subjects. In the vitamin D insufficient group, chronological age was 8.96±1.72 years, mean height (z-score [z]) was 0.51±1.26, mean BMI (z) was 0.81±2.20, and bone age was 10.26±1.75 years. In the vitamin D sufficient group, chronological age was 9.61±1.77 years, mean height (z) was-0.66±0.98, mean BMI (z) was-0.01±1.16, and bone age was 9.44±2.12 years. A paired t-test showed that three months after vitamin D administration, the mean 25-OH vitamin D3 level in the insufficient group increased to 24.38 ±10.03 ng/mL and mean BMI (z) decreased to 0.67±1.06.

CONCLUSION

In Korean school-aged children, vitamin D insufficiency were relatively higher and may be closely related with higher BMI. Insufficient rise of the level of vitamin D after supplementation suggest the new supplementation guidelines, especially for Korean children.

Hypovitaminosis D in the Middle East and North Africa: Prevalence, risk factors and impact on outcomes

BACKGROUND

The Middle East and North Africa (MENA) region registers some of the highest rates of hypovitaminosis D worldwide.  

AIM

We systematically reviewed the prevalence of hypovitaminosis D, rickets and osteomalacia, their predictors and impact on major outcomes, in the region.

METHODS

Medline, Pubmed and Embase search engines, entering keywords and concepts, combined with individual countries of interest, were used. Search was limited years 2000-2012; and review articles were used for the period preceding year 2000.

RESULTS

Rickets and osteomalacia still occur in this sunny region. Hypovitaminosis D prevails, with rates varying 30-90%, considering a desirable serum 25 hydroxy-vitamin D [25(OH)D] of 20 ng/ml. Advancing age, female gender, multi-parity, clothing style, season, socio-economic status and urban living are recognized predictors of hypovitaminosis D in adults. Prolonged breastfeeding without vitamin D supplementation and low dietary calcium intake are the recognized risk factors for rickets and hypovitaminosis D in children.. Associations with pain score and disease activity in rheumatologic disorders, viral load and interleukins in hepatitis C, BMI, lipids and insulin sensitivity, blood pressure, heart failure and mortality are described. Sun exposure in adults decreased prevalence of metabolic syndrome in one study. Few randomized vitamin D trials revealed that the majority of mothers or children failed to achieve a desirable 25(OH)D level, even with doses by far exceeding current recommendations. A trial in adolescent girls reveals substantial bone and lean mass increments.

CONCLUSION

Hypovitaminosis D is prevalent in MENA. The lack of populations based studies, gaps in studies in infants, pre-pubertal children and pregnant women, hinder the development of region specific guidelines and constitute a major obstacle to impact this chronic and most often subclinical disease.

Vitamin D status in Montréal preschoolers is satisfactory despite low vitamin D intake

The 2007 to 2009 Canadian Health Measures Survey reported vitamin D status in a representative sample of Canadians (6-79 y); however, children <6 y were not assessed. Our objective was to measure vitamin D intake from food and supplements, sun exposure, and biological vitamin D status of children ages 2 through 5 y in Montréal (latitude 45°N). Preschoolers (n = 508) were recruited between June 2010 and 2011 in a random sample of licensed daycares in the regions of greater Montréal, Canada in a cross-sectional study. The total plasma 25-hydroxyvitamin D [25(OH)D] concentration was measured using a chemiluminescence assay (Liaison, Diasorin). Dietary intake was assessed during one 24-h period plus a 30-d FFQ. Socioeconomic, demographic, anthropometry, and sun exposure data were collected. Plasma 25(OH)D was ≥50 nmol/L in 88% of children, whereas 49.4% had concentrations ≥75 nmol/L during the 1-y study. Almost 95% of preschoolers had vitamin D intakes less than the Estimated Average Requirement (EAR), and 4.8% of preschoolers ≤3.9 y and 25.9% of preschoolers ≥4 y had calcium intakes less than the EAR. Plasma 25(OH)D was different across age, income, sun index, milk intake, and dietary and supplemental vitamin D intake tertiles. Despite vitamin D intakes less than the EAR, the vitamin D status of Montréal preschoolers attending daycare is mostly satisfactory even in winter, suggesting that the EAR value is too high in the context of typical exogenous intakes of vitamin D in North America.

Vitamin D status and associated factors in recent-onset type 1 diabetic children in Iran

Background

In this study, the prevalence of vitamin D deficiency was assessed in a group of children and adolescent patients with recent-onset type 1 diabetes mellitus (T1DM).

Methods

Fifty-three patients with age 8–18 years and duration of T1DM less than 8 weeks were recruited. A food frequency questionnaire (FFQ) was used to assess dietary vitamin D and calcium intake. Sunshine exposure was measured using a questionnaire to quantify the amount of time children spent in the sun and other sun-related habits, and a sun index score was generated. Serum 25(OH)D < 20 ng/ml was considered as vitamin D deficiency. Logistic regression was used to assess predictors of vitamin D deficiency.

Results

All patients were vitamin D deficient (77%) or insufficient (23%). In a logistic regression model, it was shown that the risk of being vitamin D deficient was significantly decreased by sunlight exposure ≥ 15 minutes during the weekends versus < 15 minutes (OR: 0.06, 95% CI: 0.01–0.75; P=0.029). In addition, vitamin D deficiency in boys was lower than girls in this model (OR: 0.164 [95% CI: 0.02–1.11]; P = 0.063).

Conclusion

Vitamin D deficiency is highly prevalent among children and adolescents with T1DM in Iran. Boys and children with ≥ 15 minutes sunlight exposure in weekends were less likely to be vitamin D deficient than girls and those with < 15 minutes sunlight exposure.

[Vitamin D: pathophysiology and clinical applicability in paediatrics]

Vitamin D has always been associated with calcium -phosphate metabolism, but vitamin D receptors or its metabolites have been found in different body cells, indicating a possible involvement in other physiological mechanisms. Vitamin D deficiency has been associated with an increased risk of infections, autoimmune diseases, diabetes, metabolic syndrome, obesity, asthma and certain neurological diseases such as schizophrenia. Currently there are different techniques for measuring 25 (OH) cholecalciferol in blood, but the results are variable and controversial. It is important to achieve standardization of these techniques to be able to compare the results obtained in different studies. Normal physiological vitamin D levels have not yet been established, but they must be higher than 20 ng/ml (50 nmol/l) in order to perform it physiological function. It is still under discussion on how to achieve these minimum levels. Since the main source of vitamin D is sunlight, we should look for strategies that do not contradict the messages of prevention of skin cancer. In recent years, recommendations for vitamin D intake have changed, involving prophylactic activities carried out in Primary Care. This manuscript reviews the physiology, actions, laboratory determination, desirable levels, and vitamin D intake recommendations, and it highlights many questions raised by new research.