Seasonal vitamin D status of healthy schoolchildren and predictors of low vitamin D status.

Abstract

OBJECTIVES:

The aim of the study was to assess seasonal prevalence of vitamin D deficiency according to sex and to determine the relations between serum levels of 25-hydroxyvitamin D [25(OH)D] and parathyroid hormone (PTH) and sociodemographic characteristics in otherwise healthy schoolchildren during spring and autumn.

METHODS:

In a cross-sectional study, 746 healthy students aged between 11 and 18 years were recruited during spring (n = 375) and autumn (n = 371). Sociodemographic data were collected by a questionnaire. Serum 25(OH)D, PTH, calcium, phosphate, and alkaline phosphatase were measured. Serum 25(OH)D levels were categorized as <50 nmol/L (vitamin D deficiency) and <25 nmol/L (severe deficiency).

RESULTS:

Mean ± standard deviation 25(OH)D levels were 22.3 ± 10.5 nmol/L in girls and 28.5 ± 17.0 nmol/L in boys during spring (P < 0.001) and 36.5 ± 20.3 nmol/L in girls and 45.0 ± 18.5 nmol/L in boys during autumn (P < 0.001). The prevalence of vitamin D deficiency was 93% during spring and 71% during autumn. There was a negative correlation between 25(OH)D and PTH levels (P < 0.01). We determined a cutoff point of serum 25(OH)D in which the mean serum PTH concentration began to increase as 35.8 nmol/L (P < 0.0001). The age, sex, and calcium level were found to be independent predictors for vitamin D deficiency.

CONCLUSIONS:

Vitamin D deficiency is prevalent among healthy schoolchildren. It is noteworthy that 25(OH)D levels were significantly lower in girls and during autumn. We recommend vitamin D supplementation for children in addition to more time spent for outdoor activities for sensible sunlight exposure.

• Authors: Gülay Karagüzel, Beril Dilber, Gamze Çan, Ayşenur Ökten, Orhan Değer, Michael F Holick
• Journal: Journal of pediatric gastroenterology and nutrition (J Pediatr Gastroenterol Nutr) Vol. 58 Issue 5 Pg. 654-60 (May 2014) ISSN: 1536-4801 [Electronic] United States
• PMID: 24787093 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Parathyroid Hormone
• Vitamin D
• 25-hydroxyvitamin D

Topics

• Adolescent
• Child
• Cross-Sectional Studies
• Dietary Supplements
• Exercise
• Female
• Humans
• Male
• Parathyroid Hormone (blood)
• Seasons
• Sex Factors
• Sunlight
• Surveys and Questionnaires
• Vitamin D (administration & dosage, analogs & derivatives, blood)
• Vitamin D Deficiency (blood, epidemiology, prevention & control)