Abstract
Background/Objectives:Vitamin D deficiency may contribute to endocrine health and disease (diabetes, autoimmune thyroid diseases, polycystic ovarian syndrome, etc.). The aim of this study was to determine the prevalence and specific factors for hypovitaminosis D among children stratified by body mass index (BMI) in Northern Spain.Subjects/Methods:A cross-sectional clinical (sex, age, season of study visit, place of residence and BMI) and blood testing (calcium, phosphorous, calcidiol and parathyroid hormone (PTH)) were accomplished in 546 Caucasian individuals (aged 3.2–15.8 years). The BMI (Z-score) allowed establishing four groups: normal, overweight, obesity and severe obesity. The criteria of the US Endocrine Society were used for the definition of hypovitaminosis D.Results:Calcidiol levels were significantly higher in normal and overweight groups (P=0.001), whereas PTH levels were significantly higher in obesity and severe obesity groups (P=0.001). Hypovitaminosis D prevalence was significantly higher in severe obesity (81.1%) and obesity (68.2%) groups, whereas was lowest in overweight (55%) and normal (58.1%) groups (P=0.001). There was a negative correlation between calcidiol and PTH levels (P<0.01). Female (90.9%), adolescent group (88,2%), winter (100%) and autumn (82.4%) time and urban residence (94.1%) imply a higher prevalence of hypovitaminosis D in subjects with severe obesity (P<0.001). Female, puberal age, autumn, winter and spring time, urban residence and severe obesity were found to be independent predictors for hypovitaminosis D.Conclusions:Severe obesity could be considered as an associated factor for vitamin D deficiency, and, owing to its high prevalence, the implementation of systematic screening and hypovitaminosis treatment programs would be particularly useful.
Highlights
Vitamin D and parathyroid hormone (PTH) are well known because of their role in bone metabolism and calcium homeostasis
Calcidiol was determined by a high-specific chemiluminiscence-immunassay (LIAISON Assay, Diasorin, Dietzenbach, Germany) with intra- and interassay coefficient of variation of 4.2–9.5% and 7.6–2.1%, respectively, and functional sensitivity of 4.0 ng ml − 1
Age, season of the year and place of residence have been described as independent factors as it was associated with hypovitaminosis D,3,5,10–15 as indicated by the results of logistic analysis in this study; in this case, the analysis did not detect significant differences in the distribution of nutritional status in relation to this factors, except for a different proportion of individuals with obesity/severe obesity in the adolescent group, which was slightly higher
Summary
Vitamin D and parathyroid hormone (PTH) are well known because of their role in bone metabolism and calcium homeostasis. Vitamin D deficiency leads to less absorption of dietary calcium and increased PTH secretion to maintain normal levels of serum calcium. Age, race, season of the year in which serum is collected, sun exposure and childhood obesity have been associated with lower levels of serum calcidiol.[3,5,10,11,12,13,14,15] Vitamin D deficiency in obese individuals is attributed to several factors, such as decreased exposure to sunlight in obese subjects because of sedentary lifestyle, or to excessive vitamin sequestration within adipose tissue.[2,3,11,16] Fractures, tibia vara and slipped capital femoral epiphysis are more common in obese children perhaps because of decreased bone density in a setting of vitamin D deficiency.[17] data on prevalence of vitamin D deficiency among children, stratified by body mass index (BMI) categories (normal weight, overweight, obesity and severe obesity), may inform about the need for screening and treatment
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