Can vitamin D status be assessed by serum 25OHD in children?

Vitamin D status of children with moderate to severe chronic Kidney Disease at a Tertiary Pediatric Center in Cape Town

The prevalence of suboptimal Vitamin D levels is higher in patients with chronic kidney disease (CKD) than in the general population. Recent findings suggest that progression of CKD is linked to a suboptimal Vitamin D level. A high percentage of CKD patients have severe Vitamin D deficiency. These patients also have a low level of 25-hydroxy-vitamin D [25(OH)D] and consequently, a reduced ability to form active 1,25-dihydroxyvitamin D. Various factors underlie the low level of 25(OH)D, including a sedentary lifestyle, decreased intake of Vitamin D due to CKD-related dietary restrictions, and decreased synthesis of Vitamin D in skin due to uremia. All these factors may be particularly influential in patients with progressively worsening CKD, including those receiving chronic dialysis. The objective of our study is to determine the prevalence of Vitamin D deficiency in children with CKD stages three to five and those receiving chronic dialysis, to ascertain whether there is a relationship between Vitamin D deficiency and the stage of CKD, and to identify any clinical correlates associated with the Vitamin D status. A single-center, retrospective review was conducted of 46 children (younger than 18 years) with CKD stages 3-5D who attended the renal clinic of the Red Cross Children's Hospital between October 2013 and November 2014. In total, 73.9% of the study population had suboptimal Vitamin D levels (43.5% and 30.4% had Vitamin D deficiency and insufficiency, respectively). The prevalence of Vitamin D deficiency was significantly higher in older children (≥10 years of age) than in younger children (P = 0.000) but did not significantly differ between males and females (P = 0.693). In total, 12 of 15 black children (80%), 19 of 26 colored children (73.1%), two of four white children (50%), and one Asian child (100%) had suboptimal Vitamin D levels. Neither white nor Asian child had Vitamin D deficiency. In addition, 90% of patients undergoing chronic dialysis, 80% of whom were receiving peritoneal dialysis, had suboptimal Vitamin D levels. Age, weight, height, and the albumin concentration were significantly associated with the Vitamin D level. There was a positive linear relationship between the Vitamin D level and the serum albumin concentration (Spearman's rho correlation coefficient = 0.397, P = 0.007). In total, 87.5% of patients with nephrotic-range proteinuria had suboptimal Vitamin D levels, and 80% were Vitamin D deficient (P = 0.004). A higher percentage of Vitamin D deficiency/insufficiency cases was documented during the winter (24/34, 70.6%) than during the summer (10/34, 29.4%); however, this difference was not statistically significant (P = 0.685). Sub-optimal Vitamin D is high among children with moderate to severe CKD and significantly higher in those undergoing chronic dialysis. The emerging evidence of the role of Vitamin D in slowing progression of CKD highlights the need for monitoring and correction of Vitamin D levels in predialysis children.

Importance of vitamin D in acute and critically ill children with subgroup analyses of sepsis and respiratory tract infections: a systematic review and meta-analysis

OBJECTIVES

To estimate the prevalence of 25-hydroxyvitamin D (25(OH)D) deficiency and investigate its association with mortality in children with acute or critical conditions.

DESIGN

Systematic review and meta-analysis of observational studies.

DATA SOURCES

PubMed, OVID, Google Scholar and the Cochrane Library searched until 21 December 2018.

ELIGIBILITY CRITERIA

Studies of children hospitalised with acute or critical conditions who had blood 25(OH)D levels measured.

DATA EXTRACTION AND SYNTHESIS

We obtained pooled prevalence estimates of 25(OH)D deficiency and ORs for mortality. We calculated 95% CI and prediction intervals and investigated heterogeneity and evidence of small-study effects.

RESULTS

Fifty-two studies were included. Of 7434 children, 3473 (47.0%) were 25(OH)D deficient (<50 nmol/L). The pooled prevalence estimate of 25(OH)D deficiency was 54.6% (95% CI 48.5% to 60.6%, I²=95.3%, p<0.0001). Prevalence was similar after excluding smaller studies (51.5%). In children with sepsis (18 studies, 889 total individuals) prevalence was 64.0% (95% CI 52.0% to 74.4%, I²=89.3%, p<0.0001) and 48.7% (95% CI 38.2% to 59.3%; I²=94.3%, p<0.0001) in those with respiratory tract infections (RTI) (25 studies, 2699 total individuals). Overall, meta-analysis of mortality (18 cohort studies, 2463 total individuals) showed increased risk of death in 25(OH)D deficient children (OR 1.81, 95% CI 1.24 to 2.64, p=0.002, I²=25.7%, p=0.153). Four (22.0%) of the 18 studies statistically adjusted for confounders. There were insufficient studies to meta-analyse sepsis and RTI-related mortality.

CONCLUSIONS

Our results suggest that 25(OH)D deficiency in acute and critically ill children is high and associated with increased mortality. Small-study effects, reverse causation and other biases may have confounded results. Larger, carefully designed studies in homogeneous populations with confounder adjustment are needed to clarify the association between 25(OH)D levels with mortality and other outcomes.

PROSPERO REGISTRATION NUMBER

CRD42016050638.

Vitamin D deficiency in children: a challenging diagnosis!

The concern about the assessment of vitamin D status is growing. Numerous publications warn about the high prevalence of vitamin D deficiency, as well as the potential role of vitamin D in non-bone health outcomes. The status of vitamin D is usually assessed by measuring serum total 25-hydroxyvitamin D (25OHD) concentration. This is the major circulating form of vitamin D and keeps an inverse correlation with serum parathyroid hormone (PTH) concentration. A value of 25OHD of 20 ng/ml is generally assumed as threshold of vitamin D sufficiency in epidemiologic studies because serum PTH tends to increase when the 25OHD concentration stands below this value. In pediatric population, very few studies have analyzed this issue and the negative relationship between serum 25OHD and serum PTH is not clear, which is the suitable circulating concentration of 25OHD and the threshold of deficiency being matters of controversy. The majority of 25OHD circulates in serum tightly bound to a globulin (DBP). According to the free hormone hypothesis, protein-bound hormones are not biologically available and it is the free form that exerts or facilitates the physiologic actions. If this is true, factors that affect DBP may alter the interpretation of total serum 25OHD measurements.

Marker of vitamin D status in healthy children: Free or total 25-hydroxyvitamin D?

OBJECTIVE

To assess if serum free 25-hydroxyvitamin D (25OHD) is a better indicator of vitamin D status than total 25OHD in healthy children.

METHODS

Cross-sectional prospective clinical study was designed. We measured serum free 25OHD concentrations and its correlation with calculated free 25OHD, total 25OHD, intact parathyroid hormone (PTH), and vitamin D binding protein (DBP) in children. The influence of age, sex, ethnicity, body mass index (BMI), season of the year, diet intake, vitamin supplements, time spent outdoors and albumin concentrations on free 25OHD was also analyzed. 241 children aged from 0 days to 14 years, and living in the northern Spain (latitude 43° N), were included.

RESULTS

Mean (SD) free 25OHD concentrations were 2.48 (1.39), 5.46 (3.12), 4.12 (1,72), 3.82 (1.43) pg/ml in children aged 0 days, 1 month-2 years, 2-6 years and >6 years, respectively. Correlation between directly measured and calculated free 25OHD was high and significant (r = 0.66) as well as the correlation between serum free and total 25OHD concentrations (r = 0.61). No significant correlation was found between PTH and free 25OHD (r = -0.08). The total 25OHD and PTH concentrations' correlation was inverse (r = -0.25) and significant. Neither free nor total 25OHD concentrations correlated with DBP concentrations. Among the analyzed variables, free 25OHD values were higher in spring/summer than in autumn/winter in children older than 6 years.

CONCLUSIONS

: These findings do not support that free 25OHD is a better marker of vitamin D deficiency than total 25OHD in healthy pediatric population.

Do all infants need vitamin D supplementation?

A high prevalence of vitamin D deficiency (VDD) in children has been observed worldwide, but there are few studies on the nutritional status of vitamin D (VD) in healthy infants. The main cause of deficiency in healthy children is breastfeeding without supplementation and lack or insufficiency of sun exposure. The aims of this study were to determine serum concentrations of 25(OH)D and verify its association with parathyroid hormone (PTH) concentrations and use of VD supplementation in healthy infants aged ≥ 6 to ≤ 24 months attended at two Primary Health Care Units in Ribeirão Preto city, São Paulo, Brazil. A cross-sectional, observational and analytical study was performed in which serum concentrations of 25(OH)D, PTH, alkaline phosphatase (AP), calcium (Ca), phosphorus (P) and albumin were determined in 155 healthy infants. Information on sun exposure, sociodemographic aspects of mothers and clinical and nutritional characteristics of infants were obtained through interviews with responsible infants’s legal representatives. Ten infants (6%) presented deficient 25(OH)D serum concentration (≤20ng/ml) and 46 (30%), insufficient (21 to 29ng/ml). No changes in serum P, Ca and albumin concentrations were detected. Only one infant had an increase in PTH serum concentrations. 35% (55/155) of infants had high AP e 40% (22/55) presented insufficient serum concentrations of 25(OH)D but none presented deficient ones. There was a weak association between serum concentrations of 25(OH)D and PTH and an association between serum concentrations of 25(OH)D and P when adjusted for sex, age and BMI. There were no associations between inadequate serum concentrations of 25(OH)D (deficient ou insufficient), sun exposure and VD supplementation. This study found a low prevalence of deficient 25(OH)D serum concentration and high prevalence of insufficient ones which was not associated with changes in serum PTH, AP, P, Ca and albumin concentrations, VD supplementation and the formula volume intake.

The roles of vitamin D and dietary calcium in nutritional rickets

The etiology and pathogenesis of nutritional rickets are becoming progressively clearer. Vitamin D deficiency has generally been considered the major or only player in the pathogenesis of nutritional rickets. However, recent research into calcium deficiency has now provided clinicians with reasons to investigate and manage patients with nutritional rickets more appropriately.

The important question when assessing cases of nutritional rickets is: “Is it calcium or vitamin D deficiency or both that play a major role in the pathogenesis of the disease?”

The case presentation in this review highlights the risk factors, clinical presentation and pathophysiology of nutritional rickets in a young South African black child from a semi-urban area in Johannesburg, a city with abundant sunshine throughout the year.

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Vitamin D and calcium deficiencies play synergistic roles in nutritional rickets.

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Dietary calcium intake of <300 mg/day increases the risk of nutritional rickets.

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Vitamin D status is worsened by dietary calcium deficiency itself.

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Marked elevation of 1,25-dihydroxyvitamin D is characteristic of calcium deficiency.

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Preventative strategies needed to decrease the prevalence of nutritional rickets.

A systematic review of vitamin D status in southern European countries

PURPOSE

Despite an acknowledged dearth of data on serum 25-hydroxyvitamin D (25(OH)D) concentrations from Southern European countries, inter-country comparison is hampered by inconsistent data reporting. The purpose of the current study was to conduct a systematic literature review of available data on serum 25(OH)D concentrations and estimate vitamin D status in Southern European and Eastern Mediterranean countries, both at a population level and within key population subgroups, stratified by age, sex, season and country.

METHODS

A systematic review of the literature was conducted to identify and retrieve scientific articles reporting data on serum 25(OH)D concentration and/or vitamin D status following standard procedures.

RESULTS

Data were extracted from 107 studies, stratified by sex and age group, representing 630,093 individuals. More than one-third of the studies reported mean 25(OH)D concentrations below 50 nmol/L and ~ 10% reported mean serum 25(OH)D concentrations below 25 nmol/L. Overall, females, neonates/ infants and adolescents had the higher prevalence of poor vitamin D status. As expected, there was considerable variability between studies. Specifically, mean 25(OH)D ranged from 6.0 (in Italian centenarians) to 158 nmol/L (in elderly Turkish men); the prevalence of serum 25(OH)D < 50 nmol/L ranged from 6.8 to 97.9% (in Italian neonates).

CONCLUSIONS

Contrary to expectations, there was a high prevalence of low vitamin D status in the Southern Europe and the Eastern Mediterranean regions, despite abundant sunshine. These data further emphasize the need for strategies, such as fortification of foods with vitamin D and/or vitamin D supplementation, which will be tailored to the needs of specific population groups with higher risk of insufficiency or deficiency, to efficiently tackle the pandemic of hypovitaminosis D in Europe.

The etiology and significance of fractures in infants and young children: a critical multidisciplinary review

This paper addresses significant misconceptions regarding the etiology of fractures in infants and young children in cases of suspected child abuse. This consensus statement, supported by the Child Abuse Committee and endorsed by the Board of Directors of the Society for Pediatric Radiology, synthesizes the relevant scientific data distinguishing clinical, radiologic and laboratory findings of metabolic disease from findings in abusive injury. This paper discusses medically established epidemiology and etiologies of childhood fractures in infants and young children. The authors also review the body of evidence on the role of vitamin D in bone health and the relationship between vitamin D and fractures. Finally, the authors discuss how courts should properly assess, use, and limit medical evidence and medical opinion testimony in criminal and civil child abuse cases to accomplish optimal care and protection of the children in these cases.

Comparison of the Vitamin D Status of Children Younger and Older Than 2 Years in Tehran: Are Supplements Really Necessary?

BACKGROUND

Vitamin D is a vital lipid-soluble vitamin in the body, helping the growth and development of bones. Vitamin D deficiency in children has several adverse effects. The most important preventative factor is determining the deficiency at an early stage and prescribing vitamin D-containing supplements.

OBJECTIVES

To investigate the vitamin D status of children younger and older than 2 years and determine the utility of prescribing vitamin D supplements.

PATIENTS AND METHODS

Three hundred healthy children who attended the pediatric clinic for routine assessments were enrolled in this study. Their parents were asked to complete a questionnaire, which included questions about demographics, nutrition, and supplements. Blood levels of vitamin D, calcium, and phosphorus were then measured.

RESULTS

The final study consisted of 286 children, 140 males and 146 females, with a mean age of 4.46 ± 2.82 yr. Of these, 218 (76.22%) children, with a mean age of 5.09 ± 2.82 yr, had vitamin D deficiency, and 76 children (23.78%), with a mean age of 2.58 ± 1.88 yr, had normal vitamin D levels (P = 0.001). The mean level of vitamin D was 29.71 ± 14.42 ng/mL in 88 (30.8%) patients up to 2 years and 17.11 ± 14.02 ng/mL in 198 (69.2%) patients older than 2 years (P = 0.0001).

CONCLUSIONS

The vitamin D levels of children aged more than 2 years are lower than those of children aged less than 2 years. Thus, prescribing vitamin D-containing supplements in children older than 2 years may be beneficial.