Vitamin D deficiency--it's more than rickets

Factors influencing initiation and discontinuation of vitamin D supplementation among children 1-24-months-old

OBJECTIVES

To determine vitamin D supplementation frequency among children aged 1-24 months, factors that influence adherence, and reasons for discontinuation of initiated vitamin D.

METHODS

This cross-sectional study was conducted using a questionnaire administered to the mothers via face-to-face interview of 560 children aged from 1 to 24 months admitted to outpatient clinics from June to December 2017.

RESULTS

A total of 351 children were administered vitamin D, and the rate of supplementation in the first year of life was 83%, while it was only 28% between 13 and 24 months. The rate of vitamin D supplementation was higher among exclusively formula-fed children (p < .05). When the data were analyzed using logistic regression analysis, only visit family physicians were statistically significant independent variable in increasing supplementation (p < .05). Compared with family refusal, the rate of discontinuation of vitamin D by the healthcare providers was higher after the first year of life (p < .05). The rate of vitamin D discontinuation by healthcare providers, especially by nurses who considered the duration of supplementation adequate, was statistically significantly higher when compared with the fontanel closure and other independent variables (p < .05).

CONCLUSION

The rate of vitamin D supplementation was higher among families who visited family physicians, which suggests the importance of well-baby visits. Since vitamin D supplementation was less common among exclusively breastfed children, mothers should be educated. Healthcare professionals need further education about the importance of vitamin D supplementation and indications for discontinuation.

The Pattern of Vitamin D Levels in Children 0-4 Years of Age in Yunnan Province

OBJECTIVE

Vitamin D is an essential nutrient that regulates the activity of calcium and bone hormones throughout life; however, vitamin D levels in children, which is the most crucial period during human development, has not been established.

METHODS

As the first descriptive study of serum vitamin D levels in children in Yunnan Province, we determined the serum vitamin D levels in children 0‒4 years of age who underwent physical examinations at Kunming Children's Hospital, and the association between the serum vitamin D level and the calcium, phosphorus and alkaline levels.

RESULTS

Vitamin D levels in children were highest in the summer months and lowest in the winter months. Vitamin D deficiency was more common in girls than boys. A social-economic effect was shown, as evidenced by the significantly higher serum vitamin D levels in children from the top five cities compared with the lower-ranked cities. Moreover, we also demonstrated a significant correlation between vitamin D and serum calcium levels.

CONCLUSION

Our study suggested that sex and age affected the vitamin D levels of children, and a reasonable reference range in children 0-4 years of age in Yunnan Province was determined.

Prevalence of vitamin D deficiency in pregnant women and their babies in Bhaktapur, Nepal

Background

Vitamin D deficiency has been observed worldwide in pregnant women and their newborns. Maternal vitamin D deficiency can lead to deficiency in their newborn baby and has been linked with various complications during pregnancy and delivery. There is risk of premature delivery and it is associated with high neonatal mortality.

Methods

Seventy-nine pregnant women who were admitted to the Siddhi Memorial Hospital for delivery and their newborn babies were enrolled in the study. Maternal blood samples were taken before delivery while umbilical cord blood samples of their babies were taken after delivery. Serum vitamin D level and calcium level were assessed by fluorescence immunoassay using Ichromax vitamin D kit and endpoint method, respectively in the Siddhi Memorial Hospital laboratory.

Results

Mean +/− SD serum vitamin D and calcium levels in pregnant mother before delivery were 14.6 +/− 8.5 ng/ml and 8.0 +/− 0.5 mg/dl, respectively, and in the cord blood were 25.7 +/− 11.2 ng/ml and 8.6 +/− 0.9 mg/dl, respectively. Eighty-one percent of the mothers and 35.8% of their babies were found to have vitamin D deficiency. Although 97.5% of the pregnant women were taking calcium supplementation, serum calcium was found lower than the normal reference value in 67% of the pregnant women and 64.2% of their babies. There were a linear relationship between the maternal and baby’s serum vitamin D (P < 0.001) and calcium (P < 0.001) levels.

Conclusion

There is high prevalence of vitamin D and calcium deficiency in pregnant mothers and newborn babies in Bhaktapur, Nepal. Pregnant women need to be supplemented with adequate amounts of these nutrients.

It is not always child abuse: multiple fractures due to hypophosphatemic rickets associated with elemental formula use

Rickets is not a disease of the past. We described a toddler who developed hypophosphatemic rickets associated with the use of elemental formula. This case highlights the importance of frequent monitoring of mineral metabolism in children receiving elemental formula and considering rickets in the workup of child abuse.

Evaluation of vitamin D prophylaxis in 3-36-month-old infants and children

BACKGROUND

Vitamin D (VD) deficiency (VDD) is still a population-based health problem that affects people at different ages. The aim of this study was to evaluate VD prophylaxis for the prevention of VDD in (3-36)-month-old infants and children.

METHODS

Infants and children aged between 3 and 36 months, with different etiologies, admitted to outpatient and inpatient clinics from October 2010 to October 2011 at the Children's Hospital of Erciyes University, were enrolled for the study. Their VD intake (if used; time of initiation, dosage and compliance) and nutritional status (breast-fed, formula or complementary fed) were noted. In order to study seasonal VD changes, the levels of serum calcium, phosphorus and magnesium, alkaline phosphatase activity (PLA), plasma parathyroid hormone (PTH) and 25 hydroxyvitamin 25(OH)D levels were measured at the beginning of VD supplementation during the four seasons.

RESULTS

A total of 316 subjects were enrolled in the study, consisting of 202 (63.9%) outpatient and 114 (26.1%) inpatient groups. From these subjects, 304 (96.2%) were supplemented with VD; whereas 12 (3.8%) were not. Out of the subjects supplemented with VD, 237 (75%) initiated VD after the second week of life, 267 (87.8%) were given three drops of VD daily and 209 (66.1%) had taken VD regularly. The plasma 25(OH)D levels were found to be lower in the inpatient group than the outpatient group (29.35 ng/mL and 34.35 ng/mL, respectively). The plasma 25(OH)D levels were lower during the spring and winter. VDD and VD insufficiency (VDI) was found in 31 (9.8%) and 30 (9.5%) subjects, respectively.

CONCLUSIONS

The plasma 25(OH)D levels were lower in inpatient and breast-fed only subjects and in winter and spring. The national VD augmentation program seems to be beneficial for the prevention of VDD, but VDD/VDI seems to still be an important health problem.

Adverse effects of imatinib in children with chronic myelogenous leukemia

BACKGROUND

Imatinib mesylate (IM) is a selective tyrosine kinase inhibitor and is approved for indefinite treatment of pediatric chronic myelogenous leukemia (CML). Potential side-effects regarding growth failure and bone metabolism have been reported but data are still scarce in pediatric CML.

METHODS

Six chronic-phase CML children on IM treatment with a median age of 9.87 years (range, 5.33-12.67 years) were enrolled in the study. Growth, bone mineral density (BMD), bone parameters, 25(OH)-vitamin D3 (25-OHD3) and blood tests including parathyroid hormone, insulin-like growth factor-1 (IGF-1), IGF binding protein 3, thyroid function test and sex hormones were assessed.

RESULTS

Median duration of IM treatment was 78.5 months. Height velocity was suppressed during the first 30 months of treatment and improved gradually afterwards. Two patients (33.3%) had decreased lumbar spine BMD z-scores (<1.5 SD). Patients with decreased BMD had higher mean IM exposure time than those with normal BMD. The majority of patients (n = 5) had low 25-OHD3 (<30 ng/mL), but there was no correlation between BMD and 25-OHD3 status. Other blood tests were normal.

CONCLUSIONS

This study supports and confirms the need for monitoring the side-effects of IM treatment on growth, bone density and vitamin D status in pediatric CML. Prolonged IM treatment was associated with low BMD without disturbing bone parameters. There was high prevalence of vitamin D insufficiency. Therefore, the beneficial effect of vitamin D supplement should be explored with regard to the effects on height velocity and BMD in CML patients with vitamin D insufficiency.

Relationship between newborn craniotabes and vitamin D status

OBJECTIVE

In recent studies, vitamin D deficiency during pregnancy and early infancy has been reported to predispose children to many chronic diseases, except those of the skeletal system. The aim of this study was to investigate whether craniotabes in otherwise healthy newborns is physiological, its relationship to vitamin D deficiency and whether or not it requires treatment.

METHODS

A total of 150 healthy newborns with a weight of over 2000 g were included. Newborns were divided into two groups during postnatal discharge (1-3.'s day): those with and without craniotabes. The 25-hydroxy (OH) vitamin D levels of the newborns' mothers were measured, and all infants were re-evaluated for craniotabes, as well as tested to determine levels of serum calcium (Ca), phosphorus (P), alkaline phosphatase (ALP), parathyroid hormone (PTH) and 25(OH) vitamin D, urine calcium and creatinine.

RESULTS

Craniotabes was present in 45 (30%) of newborns enrolled in the study. Craniotabes of the newborns born during the winter months was significantly higher. PTH level was significantly higher in 1-month-old newborns with craniotabes than those without craniotabes. No relationship was observed between diet and craniotabes, but in exclusively breastfed infants, vitamin D level was statistically significantly lower. No statistically significant difference was found in the occurrence of craniotabes in newborns with or without vitamin D support.

CONCLUSION

The relationship between newborn craniotabes and maternal vitamin D deficiency is not clear. However, the present study illustrates that maternal vitamin D deficiency is still a major problem. Therefore, measures to prevent maternal vitamin D deficiency should be strengthened.

Vitamin D Status among Young Children Aged 1-3 Years: A Cross-Sectional Study in Wuxi, China

BACKGROUND

The increasingly recognized importance of vitamin D has been discussed and vitamin D status among young children has attracted widespread attention in recent years. However, study on vitamin D status in young children aged 1-3 y is limited in China.

OBJECTIVE

To evaluate the nutritional vitamin D status of young children aged 1-3 y in Wuxi, southeastern China.

METHODS

A large cohort of 5,571 young children aged 1-3 y were recruited in this study who visited the child health clinics at the Wuxi Maternity and Child Health Hospital (latitude 31.57°N) during January 2014 to January 2015. Wuxi was located in southeastern China at a latitude of 31.57°N. Finger-stick blood sampling was conducted in all the subjects and serum 25-Hydroxyvitamin D (25(OH)D) levels were measured to evaluate their vitamin D status.

RESULTS

In this study, serum 25(OH)D levels of young children at the age of 1-3 years ranged from 20.6-132.9 nmol/L (Median: 71.5 nmol/L). 16.1% of the population had vitamin D deficiency (<50 nmol/L), while 38.8% of the subjects had a sufficient (50-74.9 nmol/L) vitamin D level. An optimal vitamin D status (≥75 nmol/L) was found in 45.1% of the young children. The prevalence of vitamin D deficiency was higher in autumn (19.5%) than in summer (12.1%). There was no significant difference in vitamin D status between genders. The binary logistic regression analysis revealed that child age was strongly associated with vitamin D deficiency (adjusted OR: 1.173; 95%CI: 1.053-1.308; P = 0.004).

CONCLUSIONS

The prevalence of vitamin D deficiency was 16.1% among young children aged 1-3 y in Wuxi. Season and child age were associated with their vitamin D status. It is implied that young children should receive adequate amounts of vitamin D supplementation and spend more time outdoors to prolong the sunlight exposure when they grow older.

Prevalence of classic signs and symptoms of rickets and vitamin D deficiency in Mongolian children and women

In order to assess the current nutrition status of Mongolian population, including rickets and vitamin D deficiency of children and women, the Fourth National Nutrition Cross-Sectional Survey was conducted in 21 aimags (provinces) of 4 economic regions of the country and capital city Ulaanbaatar in 2010. Children of age under five years, and non-pregnant women of reproductive age were used as subjects for assessing rickets and vitamin D deficiency. A total of 400 households were randomly selected from each of 4 economic regions and Ulaanbaatar city. Clinical examinations were performed on 706 children of age under five years. Interviews were used to assess vitamin D supplement use. The serum level of 25-hydroxyvitamin D was measured in 524 children aged 6-59 months and in 867 women of reproductive age. This survey found that 21.8% of children had vitamin D deficiency, 20.6% had low vitamin D reserve, and 30.0% of women had vitamin D deficiency and 22.2% had low vitamin D reserve. The prevalence of vitamin D deficiency in children (35.0%, 95% CI, 24.7-47.0) and women (54.9%, 95% CI 45.5-64.0) in the Eastern Region was (35.0%, 95% CI, 24.7-47.0) significantly higher than in the Western, Khangai, Central Regions, and Ulaanbaatar. Further it was found that 27.4% of children under-two years had received vitamin D supplementation. The proportion of children, who did not receive vitamin D supplementation had a higher prevalence of vitamin D deficiency than that of the children of the Eastern Region. None of the women who were involved in this survey had received vitamin D supplementation; 10.2% of them had delivered in the past 12 months, and 22.5% were breastfeeding. The prevalence of classic signs and symptoms of rickets were commonly reported among children of age under five, and skeletal abnormalities more commonly reported in children aged 12-47 months. In conclusion, there is a high prevalence of classic signs and symptoms of rickets in children of age under five years. Vitamin D supplementation in adequate doses for the prevention and treatment of rickets in children is insufficient. Thus, a trial survey is needed to assess the safe and effective doses of vitamin D supplementation necessary for the maintenance of normal serum 25-hydroxyvitamin D concentrations in Mongolian children, and women. In addition, a vitamin D food fortification program is required. This article is part of a Special Issue entitled 'Vitamin D Workshop'.

BMI but Not Race Contributes to Vitamin D-Parathyroid Hormone Axis in Peripubertal Girls

Currently, there is widespread interest in establishing 25-hydroxy vitamin D (25OHD) level preventing a secondary elevation in parathyroid hormone (PTH). The aim of this study was to identify the 25OHD nadir resulting in a rise of PTH and to determine if this inflection point is weight- or race-specific during growth and development in peripubertal girls. A total of 104 normal (n = 61) and overweight (n = 43) African American (AA) and European American (EA) girls, 5 to 14 years of age, were included. Though AAs had lower 25OHD levels, there was no difference in PTH compared with EAs. A 25OHD concentration of 27.2 ng/mL (P < .01) was indicated to increase PTH in normal-weight girls, although a statistically significant level was not established in overweight girls. No race difference in inflection point was observed. These data suggest a potential influence of weight status on the 25OHD-PTH inflection point in peripubertal girls. Accordingly, on determination of 25OHD level reflecting optimal health, consideration of weight status appears to be important during this critical period of growth and development.

Vitamin D in early childhood and the effect on immunity to Mycobacterium tuberculosis

A potential role for vitamin D as a therapeutic immunomodulator in tuberculosis (TB) has been recognised for over 150 years, but has only recently returned to the centre of the research arena due to the increasing awareness of the global vitamin D deficiency epidemic. As early as birth a child is often deficient in vitamin D, which may not only affect their bone metabolism but also modulate their immune function, contributing to the increased susceptibility to many infections seen early in life. Recent studies have begun to explain the mechanisms by which vitamin D affects immunity. Antimicrobial peptides are induced in conjunction with stimulation of innate pattern recognition receptors enhancing immunity to particular infections. In contrast the role of vitamin D within the adaptive immune response appears to be more regulatory in function, perhaps as a mechanism to reduce unwanted inflammation. In this paper we focus on the effect of vitamin D on immunity to TB. Where much of the attention has been paid by past reviews to the role of vitamin D in adult TB patients, this paper, where possible, focuses on research in paediatric populations.

Impact of vitamin D deficiency on the productivity of a health care workforce

OBJECTIVE

To define the relationship between vitamin D status and employee presenteeism in a large sample of health care employees.

METHODS

Prospective observation study of 10,646 employees of a Midwestern-integrated health care system who completed an on-line health risk appraisal questionnaire and were measured for 25-hydroxyvitamin D.

RESULTS

Measured differences in productivity due to presenteeism were 0.66, 0.91, and 0.75 when comparing employees above and below vitamin D levels of 20 ng/mL, 30 ng/mL, and 40 ng/mL, respectively. These productivity differences translate into potential productivity savings of 0.191%, 0.553%, and 0.625%, respectively, of total payroll costs.

CONCLUSIONS

Low vitamin D status is associated with reduced employee work productivity. Employee vitamin D assessment and replenishment may represent a low-cost, high-return program to mitigate risk factors and health conditions that drive total employer health care costs.

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 status and glucose homeostasis in obese children and adolescents living in the tropics

BACKGROUND

Pediatric obesity continues to rise and has become a major health problem worldwide. Vitamin D deficiency has been increasing among obese non-Asian children and is associated with abnormal glucose homeostasis in obese adults. However, data on the vitamin D status and its association with glucose homeostasis in obese children residing in tropical Asian countries are unavailable.

OBJECTIVE

To assess vitamin D status and glucose homeostasis in obese Thai children.

PATIENTS AND METHODS

A total of 150 obese, and 29 healthy non-obese children and adolescents were enrolled. Weight, height, body mass index (BMI) and waist circumference were obtained. All obese children underwent an oral glucose tolerance test with glucose and insulin measurements. Plasma 25-hydroxyvitamin D (25-OHD) and calciotropic blood chemistries were measured in all participants. Insulin sensitivity indices were calculated from the measured glucose and insulin levels.

RESULTS

Approximately 25% of the obese children and adolescents had impaired glucose tolerance, impaired fasting plasma glucose (FPG) and diabetes. Seventeen out of 150 (11.3%) obese children and 3 out of 29 (10.3%) non-obese children had vitamin D deficiency, which was defined as a 25-OHD level of <50 nmol l(-1). Glucose tolerance and insulin sensitivity indices were comparable between obese children with sufficient vitamin D and those with vitamin D deficiency. There were no relationships among serum 25-OHD; weight, height, and BMI standard deviation scores; insulin sensitivity indices; FPG and insulin; and 2-h plasma glucose and insulin levels.

CONCLUSION

Vitamin D deficiency is not as prevalent in obese Thai children as in obese non-Asian children from high-latitude countries. Adiposity per se is unlikely to be a determinant of vitamin D status in these obese individuals. There was no association between vitamin D deficiency and abnormal glucose homeostasis.

Widespread vitamin D deficiency in urban Massachusetts newborns and their mothers

OBJECTIVE

To determine vitamin D status and associated factors in a cohort of newly delivered infants and their mothers in Boston, Massachusetts.

PATIENTS AND METHODS

Enrollment in this cross-sectional study took place from 2005 to 2007 in an urban Boston teaching hospital with 2500 births per year. A questionnaire and medical-record data were used to identify variables that are potentially associated with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 20 ng/mL). Infant and maternal blood was obtained by venipuncture within 72 hours of birth. The main outcome measure was infant and maternal 25(OH)D status, assessed by competitive protein binding.

RESULTS

We enrolled 459 healthy mother/infant pairs. After subsequent exclusions, analyses were performed on 376 newborns and 433 women. The median infant 25(OH)D level was 17.2 ng/mL (95% confidence interval [CI]: 16.0-18.8; range: <5.0 to 60.8 ng/mL). The median maternal 25(OH)D level was 24.8 ng/mL (95% CI: 23.2-25.8; range: <5.0 to 79.2 ng/mL). Overall, 58.0% of the infants and 35.8% of the mothers were vitamin D deficient (25[OH]D < 20 ng/mL); 38.0% of the infants and 23.1% of the mothers were severely deficient (25[OH]D < 15 ng/mL). Risk factors for infant vitamin D deficiency included maternal deficiency (adjusted odds ratio [aOR]: 5.28 [95% CI: 2.90-9.62]), winter birth (aOR: 3.86 [95% CI: 1.74-8.55]), black race (aOR: 3.36 [95% CI: 1.37-8.25]), and a maternal BMI of >/=35 (aOR: 2.78 [95% CI: 1.18-6.55]). Maternal prenatal-vitamin use throughout the second and third trimesters was protective against infant deficiency (aOR: 0.30 [95% CI: 0.16-0.56]). Similarly, prenatal-vitamin use of > or =5 times per week in the third trimester was protective for mothers (aOR: 0.37 [95% CI: 0.20-0.69]). Despite this, >30% of the women who took prenatal vitamins were still vitamin D deficient at the time of birth.

CONCLUSIONS

A high proportion of infants and their mothers in New England were vitamin D deficient. Prenatal vitamins may not contain enough vitamin D to ensure replete status at the time of birth.

Serum 25-hydroxyvitamin D levels among US children aged 1 to 11 years: do children need more vitamin D?

OBJECTIVE

Single-center studies suggest [corrected] that hypovitaminosis D is widespread. Our objective was to determine the serum levels of 25-hydroxyvitamin D (25[OH]D) in a nationally representative sample of U.S. [corrected] children ages 1-11 [corrected] years.

METHODS

Data were obtained from the 2001-2006 National Health and Nutrition Examination Survey (NHANES). [corrected] Serum 25(OH)D levels was [corrected] determined by radioimmunoassay and categorized as <25 nmol/L, [corrected] <50 nmol/L, [corrected] and <75 nmol/L. National estimates were obtained by using assigned patient visit weights and reported with 95% confidence intervals (95% CI). [corrected]

RESULTS

During [corrected] 2001-2006, the mean serum 25(OH)D level for U.S. children ages 1 to 11 years was 68 nmol/L (95% CI, [corrected] 66-70). Children ages 6-11 [corrected] years had lower mean levels of 25(OH)D (66 nmol/L 95% CI, [corrected] 64-68) compared to [corrected] children ages 1-5 [corrected] years (70 nmol/L 95% [corrected] CI, 68-73). [corrected] Overall, the prevalence of <25 nmol/L [corrected] was 1% (95% CI, 0.7-1.4), <50 nmol/L was 18% (95% CI, [corrected] 16-21), and <75 nmol/L was 69% (95% CI, [corrected] 65-73). The prevalence of [corrected] 25(OH)D [corrected] <75 nmol/L was higher among ages [corrected] 6-11 [corrected] years (73%) compared to ages [corrected] 1-5 [corrected] years (63%); females [corrected] (71%) compared to males [corrected] (67%); and non-Hispanic black (92%) and Hispanic (80%) [corrected] compared to [corrected] non-Hispanic whites [corrected] (59%).

CONCLUSIONS

Based on [corrected] a nationally representative sample of U.S. children aged 1-11 [corrected] years, millions of children may have suboptimal levels of 25(OH)D, especially non-Hispanic black and Hispanic children. More data in children are needed not only to understand better the health implications of specific serum levels of 25(OH)D but also to determine the appropriate vitamin D supplement requirements for children.

Threshold for effects of vitamin D deficiency on glucose metabolism in obese female African-American adolescents

CONTEXT

Vitamin D status can influence insulin resistance.

OBJECTIVE

The aim of the study was to determine the prevalence of vitamin D deficiency in obese African-American (AA) adolescent females in a southeastern latitude and to determine the relationship of 25-hydroxyvitamin D [25(OH)D] with insulin and glucose dynamics.

DESIGN

We conducted a cross-sectional study in a University Children's Hospital.

METHODS

Serum 25(OH)D, fasting glucose, PTH, serum calcium, serum lipids, serum transaminases, and C-reactive protein were assessed. Indices of insulin sensitivity and resistance were determined from an oral glucose tolerance test. Subjects were classified as vitamin D deficient or sufficient, based on the traditional vitamin D deficiency definition [serum 25(OH)D <20 ng/ml] and also by a lower 25(OH)D cut-point of 15 ng/ml or less.

RESULTS

A total of 51 AA adolescent females (body mass index, 43.3 +/- 9.9 kg/m(2); age, 14 +/- 2 yr) were studied. Serum 25(OH)D concentrations were 20 ng/ml or less in 78.4% and 15 ng/ml or less in 60.8% of subjects. There were no significant group differences in the metabolic outcomes when subjects were classified using the traditional vitamin D deficiency definition. The Matsuda index of insulin sensitivity was significantly lower (P = 0.02), and insulin area under the curve was significantly higher (P = 0.04) in subjects with 25(OH)D concentrations of 15 ng/ml or less vs. those with higher concentrations.

CONCLUSIONS

Vitamin D deficiency is highly prevalent in obese, AA female adolescents and may promote insulin resistance. Our data suggest that a 25(OH)D concentration of 15 ng/ml or less may be the threshold by which vitamin D deficiency confers negative effects on insulin sensitivity.

Vitamin D insufficiency and deficiency in children with early chronic kidney disease

OBJECTIVE

To assess the prevalence of abnormal vitamin D status in children and adolescents with chronic kidney disease (CKD).

STUDY DESIGN

This was an outpatient cross-sectional, retrospective study of 258 patients, mean age 12.3 +/- 5.2 years, with an average estimated glomerular filtration rate (eGFR) of 106 +/- 51 mL/min/1.73 m2 (range, 0 to 220 mL/min/1.73 m2). Serum 25-hydroxy-vitamin D [25(OH)D], calcium, phosphorus, and parathyroid hormone levels, as well as selected anthropometric variables, were analyzed.

RESULTS

Reduced 25(OH)D concentrations (< 30 ng/mL) were found in 60% of the patients. In 28%, the concentration was < 20 ng/mL, indicating vitamin D deficiency. Patients with more advanced CKD were more likely to have vitamin D deficiency compared with those with incipient CKD or normal GFR (42% vs 26%; P = .03) and displayed more prominent hyperparathyroidism. Suboptimal vitamin D status was similar in males and females, but was significantly more prevalent in older (P < .01), non-Caucasian (P < .01), and overweight (P = .02) patients. Patients with early-stage CKD (eGFR > 60 mL/min/1.73 m2) and with vitamin D deficiency were significantly shorter than their counterparts with 25(OH)D levels > 20 ng/mL (P = .02).

CONCLUSIONS

Vitamin D insufficiency and deficiency are very prevalent in pediatric patients across all stages of CKD, particularly in non-Caucasian and obese patients, and may contribute to growth deficits during the earliest stages of CKD.

Low vitamin D status has an adverse influence on bone mass, bone turnover, and muscle strength in Chinese adolescent girls

Our goal in this cross-sectional study was to investigate the influence of low-vitamin D status on bone mass, bone turnover, and muscle strength in 301 healthy Chinese adolescent girls. Blood plasma 25-hydroxyvitamin D [25(OH)D] was measured by RIA and plasma and urine biomarkers of bone turnover were measured. Bone mineral content (BMC) and density and bone area for the whole body and the distal and proximal forearm were measured by dual energy X-ray absorptiometry. When vitamin D deficiency was defined as a serum 25(OH)D concentration of < or =50 nmol/L and severe deficiency as <25 nmol/L, 57.8% of subjects were vitamin D deficient and 31.2% were severely deficient. Multivariate analysis shows that girls with adequate vitamin D status had higher size-adjusted BMC for the whole body (P < 0.001), distal forearm (P < 0.001), and proximal forearm (P < 0.01) than those with poorer vitamin D status after adjusting for body size, handgrip strength, physical activity, and dietary intakes of calcium and vitamin D. Similar results were also found for handgrip muscle strength. Participants with adequate vitamin D status had significantly lower concentrations of bone alkaline phosphatase in plasma and deoxypyridinoline:creatinine ratio in urine compared with those of the vitamin D-deficient girls. Adolescent girls with adequate vitamin D status had significantly higher bone mass and muscle strength compared with those with poor vitamin D status. This may be attributed in part to a lower rate of bone remodeling with adequate vitamin D status. These findings suggest that adequate vitamin D status during adolescence is important for optimizing bone mass, which may lead to higher peak bone mass at maturity. Poor vitamin D status also compromises forearm muscle strength.

Vitamin D requirements in the first year of life

PURPOSE OF REVIEW

To understand the basis for current recommendations for vitamin D supplementation in childhood and the differences between the recommendations published by major expert committees, using the Medline engine of the US National Library of Medicine and the National Institutes of Health.

RECENT FINDINGS

Recent recommendations published by major national expert committees are essentially based on expert opinion (a relatively low level of evidence). Randomized controlled trials are very few, and there are no systematic reviews or meta-analyses on the topic. Most trials have examined the question of whether a specific daily vitamin D dose is capable or not to prevent rickets (by studying surrogate markers of rickets). There are no trials that have systematically attempted to determine the upper limit of daily vitamin D dose beyond which its toxic effects may appear. Whether or not outcomes such as osteoporosis (or low bone mass) and specific types of cancer may be prevented by 'generous' vitamin D supplementation is unclear and mostly based on indirect epidemiologic data not clearly substantiated by randomized controlled trials

SUMMARY

The dose of daily vitamin D supplements needed to prevent rickets is probably much lower than that recommended by most expert committees. Whether higher doses of daily vitamin D supplements may or may not prevent other poor outcomes such as adult osteoporosis or specific types of cancer is not yet known.

Niveles de 25-hidroxivitamina D en lactantes. Relación con la lactancia materna

OBJECTIVE

To determine the prevalence of subclinical vitamin D deficiency among infants in Valencia, Spain (latitude 39.5 degrees N) and its relation with breast- feeding.

MATERIAL AND METHODS

Serum levels of calcium, phosphate, alkaline phosphatase, 25-hydroxyvitamin D (25-OHD) and intact parathyroid hormone (PTH) were measured in 60 term infants aged between 1 and 6 months (mean age: 3.9 months), with no known bone, gastrointestinal or renal disease (33 exclusively breast-fed, 27 bottle-fed). Data on vitamin D supplementation and weekly direct sunlight exposure were also gathered.

RESULTS

All infants had normal serum calcium, phosphate and PTH levels. Five infants (8.3 %) had 25-OHD levels < 10 ng/ml (lower limit of normality) and all of these infants were breast-fed (15.1 % of the group). None of these five infants received vitamin D supplementation. Infants with vitamin D deficiency had slightly elevated serum alkaline phosphatase. Only 48 % of breast-fed infants received regular vitamin D supplementation. The mean serum 25-OHD concentration of breast-fed infants in winter (16.8 ng/ml) was significantly lower than that in bottle-fed infants in summer (23.6 ng/ml, p < 0.05).

CONCLUSIONS

In breast-fed infants, the association of limited sunshine exposure and poor dietary vitamin D supplementation confers a high risk of subclinical vitamin D deficiency, even in regions with a temperate climate.

Vitamin D deficiency in breastfed infants in Iowa

OBJECTIVE

The purpose of this work was to assess the vitamin D status of breastfed infants living in Iowa (latitude: 41 degrees N).

METHODS

Blood samples and dietary records from 84 breastfed infants participating in another study were used for a survey of vitamin D status at 280 days of age. The vitamin D status of those (35 infants) who did not receive preformed vitamin D at 280 days of age (unsupplemented infants) was assessed longitudinally between 112 days and 15 months of age. Plasma 25-hydroxyvitamin D and, in most cases, parathyroid hormone and alkaline phosphatase were determined.

RESULTS

At 280 days of age, 10% of breastfed infants were vitamin D deficient (25-hydroxyvitamin D < 11 ng/mL). Deficiency was significantly more prevalent among dark-skinned infants and during winter and occurred exclusively in unsupplemented infants. During winter, 78% of unsupplemented infants were vitamin D deficient. During summer, only 1 infant who had dark skin pigmentation was vitamin D deficient. Longitudinal assessment of unsupplemented infants similarly showed that the majority of breastfed infants were vitamin D deficient during winter. Severe deficiency (25-hydroxyvitamin D < 5 ng/mL) was common and was accompanied by elevation of parathyroid hormone and alkaline phosphatase. The prevalence of vitamin D deficiency decreased with age but was still 12% at 15 months of age if no preformed vitamin D was received.

CONCLUSIONS

Vitamin D deficiency, including severe deficiency, was common among breastfed infants in Iowa who did not receive preformed vitamin D. Deficiency occurred mostly during winter but was not completely absent during summer. It affected infants with light as well as dark skin pigmentation. Consumption of preformed vitamin D from vitamin supplements or formula is effective in preventing vitamin D deficiency. Vitamin D supplementation should be provided to all breastfed infants.

Nutritional rickets around the world: causes and future directions

INTRODUCTION

Nutritional rickets has been described from at least 59 countries in the last 20 years. Its spectrum of causes differs in different regions of the world.

METHODS

We conducted a systematic review of articles on nutritional rickets from various geographical regions published in the last 20 years. We extracted information about the prevalence and causes of rickets.

RESULTS

Calcium deficiency is the major cause of rickets in Africa and some parts of tropical Asia, but is being recognised increasingly in other parts of the world. A resurgence of vitamin D deficiency has been observed in North America and Europe. Vitamin D-deficiency rickets usually presents in the 1st 18 months of life, whereas calcium deficiency typically presents after weaning and often after the 2nd year. Few studies of rickets in developing countries report values of 25(OH)D to permit distinguishing vitamin D from calcium deficiency.

CONCLUSIONS

Rickets exists along a spectrum ranging from isolated vitamin D deficiency to isolated calcium deficiency. Along the spectrum, it is likely that relative deficiencies of calcium and vitamin D interact with genetic and/or environmental factors to stimulate the development of rickets. Vitamin D supplementation alone might not prevent or treat rickets in populations with limited calcium intake.

Antebrachial fractures in four captive polar bears (Ursus maritimus)

OBJECTIVE

To identify common risk factors for antebrachial fractures of captive polar bears and to evaluate outcome after fracture repair.

STUDY DESIGN

Retrospective study.

ANIMALS

Four captive polar bears.

METHODS

United States zoological collections were surveyed to determine the prevalence of fractures in captive polar bears. Medical records of captive polar bears that had antebrachial fractures were reviewed for signalment, history, physical and radiographic findings, fracture management, postoperative care, and outcome. Serum samples from healthy bears and bears with antebrachial fractures were assayed for 25-hydroxyvitamin D (25-OHD) concentrations.

RESULTS

Nineteen fractures (12 polar bears) occurred from 1974 to 2002; 12 fractures involved the antebrachium. Management of 4 antebrachial fractures was reviewed; 3 were repaired by internal fixation and 1 by external coaptation. Fractures healed and bears were returned to exhibit on average 3 months postfracture. Of 11 serum samples assayed for 25-OHD concentrations, 6 were below normal, 1 was low normal and 4 were within normal reference intervals. The 7 bears with subnormal or low normal values were housed in 2 zoos. Subnormal vitamin D concentrations were identified in 2 of 3 bears with fractures.

CONCLUSIONS

Fracture disease is not uncommon in captive polar bears. Additional research is necessary to explore the role of nutrition in polar bear fracture disease.

CLINICAL RELEVANCE

Internal fixation of antebrachial fractures is feasible and reasonably well tolerated in captive polar bears.

Breastfeeding and vitamin D status in Greece during the first 6 months of life

Since no foods are vitamin D supplemented in Greece, vitamin D status was assessed in mothers at birth and their infants up to the first 6 months of life, while they were exclusively breast-fed. This was a prospective study. Full-terms (n =35) born during the summer-autumn months and their mothers were assigned to the summer group and the remainder (n =31) to the winter group. One week after birth, serum 25-hydroxyvitamin D (25OHD) was significantly lower in the winter-born than in the summer-born neonates (6.7+/-0.7 vs. 10.1+/-0.9 ng/ml, P <0.01). The respective levels of parathyroid hormone (iPTH) were 64.9+/-13.4 and 33.9+/-4.4 pg/ml (P <0.01). The mothers had serum 25OHD levels of 10.8+/-1.0 ng/ml and iPTH levels of 15.2+/-3.5 pg/ml in the winter and 12.9+/-1.3 ng/ml and 24.8+/-4.8 pg/ml in the summer. During the 6-month follow-up, a steady increase in circulating 25OHD (up to 19.4+/-2.8 ng/ml, P <0.0001) and a decrease in iPTH (to 26.8+/-3.5 pg/ml, P =0.10) were observed in the infants born in the winter. In the summer-born infants, serum 25OHD did not change but iPTH had increased significantly by the 3rd month (59.4+/-21.8, P <0.05). Serum calcium (Ca) increased within normal limits during the study period in both groups. Serum phosphorus (Pi) started higher in the winter group (7.43+/-0.38 vs. 6.27+/-0.23 mg/dl, P <0.01) but thereafter, it was similar in both groups. Total alkaline phosphatase (ALP) increased in both groups during the study (164+/-15 vs. 219+/-17 IU/l, P <0.05 and 189+/-14 vs. 288+/-35 IU/l, P <0.001, respectively). Serum osteocalcin (OC) decreased in the winter-born neonates (32.0+/-3.4 vs. 21.5+/-3.4 ng/ml, P <0.05) and did not change in the summer group (28.9+/-3.5 vs. 26.5+/-2.8 ng/ml).

CONCLUSION

Neonates who are breast-fed exclusively during the first 6 months of life are in need of vitamin D supplementation irrespective of the season even in a sunny country like Greece where foods are not supplemented.

Vitamin D insufficiency in steroid-sensitive nephrotic syndrome in remission

Serum 25-hydroxyvitamin D [25(OH)D] concentrations are the best indicator of vitamin D nutritional status. We measured serum 25(OH)D concentrations in 94 healthy controls and in 41 subjects (aged 4-22 years) with steroid-sensitive nephrotic syndrome (SSNS) in remission. Children with remitted SSNS had significantly lower 25(OH)D concentrations than healthy controls (median 16.4 ng/ml versus 23.9 ng/ml, P<0.001). In a multivariable logistic regression model, the odds ratios (OR) of vitamin D insufficiency [25(OH)D <20 ng/ml] were independently increased in SSNS subjects [OR 11.2 (95% confidence interval 3.5-36.2)], non-whites [OR 12.9 (4.6-36.2)], older children [OR 1.20 per year (1.06-1.36)], and winter months [OR 6.7 (2.5-18.4)]. Within the SSNS subjects, multiple linear regression determined that serum 25(OH)D concentrations were not associated with SSNS disease characteristics measured in this study, such as duration of disease, number of relapses, cumulative glucocorticoids, and interval since last relapse. In conclusion, children with remitted SSNS have lower serum 25(OH)D concentrations than healthy controls. This difference persisted after adjusting for the potential confounding effects of age, race, season, and milk intake. Children with remitted SSNS may benefit from routine measurement of 25(OH)D, but the clinical significance of low 25(OH)D in this population remains unclear.

Nutritional rickets: deficiency of vitamin D, calcium, or both?

Nutritional rickets remains a public health problem in many countries, despite dramatic declines in the prevalence of the condition in many developed countries since the discoveries of vitamin D and the role of ultraviolet light in prevention. The disease continues to be problematic among infants in many communities, especially among infants who are exclusively breast-fed, infants and children of dark-skinned immigrants living in temperate climates, infants and their mothers in the Middle East, and infants and children in many developing countries in the tropics and subtropics, such as Nigeria, Ethiopia, Yemen, and Bangladesh. Vitamin D deficiency remains the major cause of rickets among young infants in most countries, because breast milk is low in vitamin D and its metabolites and social and religious customs and/or climatic conditions often prevent adequate ultraviolet light exposure. In sunny countries such as Nigeria, South Africa, and Bangladesh, such factors do not apply. Studies indicated that the disease occurs among older toddlers and children and probably is attributable to low dietary calcium intakes, which are characteristic of cereal-based diets with limited variety and little access to dairy products. In such situations, calcium supplements alone result in healing of the bone disease. Studies among Asian children and African American toddlers suggested that low dietary calcium intakes result in increased catabolism of vitamin D and the development of vitamin D deficiency and rickets. Dietary calcium deficiency and vitamin D deficiency represent 2 ends of the spectrum for the pathogenesis of nutritional rickets, with a combination of the 2 in the middle.

Issues in establishing vitamin D recommendations for infants and children

In 1963, the American Academy of Pediatrics Committee on Nutrition recommended 400 IU of vitamin D per day for all infants and children. After the late 1970s, this became an inconsistent recommendation, particularly for breast-feeding infants. In 2003, however, the Committee on Nutrition of the American Academy of Pediatrics recommended 200 IU/d vitamin D for all infants and children. This was in response to the vitamin D adequate intake recommendations made by the Institute of Medicine in 1997, the increasing number of reports of nutritional rickets in certain populations of American infants, and the Healthy People 2010 goal of having 75% of infants breast-fed for the first 6 mo of life. In making these recommendations, many issues were taken into consideration, including the following. 1) Vitamin D deficiency is more than rickets, which is the final stage of the deficient state among growing children. 2) Adequate sunlight exposure cannot be determined exactly for every subject. 3) There is new awareness of the hazards of ultraviolet-B light exposure in childhood and the subsequent development of skin cancer in adulthood. 4) There is decreasing intake of vitamin D-fortified foods among older children and adolescents. More research is needed in the pediatric population to determine the recommended dietary allowance of vitamin D. A new definition of vitamin D deficiency that would make use of normal serum concentrations of 25-hydroxyvitamin D3 in a given population is needed. The recommended intake of 200 IU/d may not be enough. More data are needed to support the adequacy of the present and possibly even higher recommended vitamin D daily intakes.