Hypovitaminosis D in healthy schoolchildren.
BACKGROUND
Vitamin D is essential for skeletal growth, but there are currently no guidelines for vitamin D supplementation after infancy. This study investigates vitamin D insufficiency in healthy children.


METHODS
Children ages 10 to 16 years from 3 private schools in Beirut, Lebanon, with differing socioeconomic status (SES) were studied: 169 in the spring of 1999 and 177 in the following fall; 83 students participated in both study phases. They had a physical examination, answered a dietary questionnaire, and blood was drawn for calciotropic hormones and indices of bone turnover.


RESULTS
Overall, 52% of the students were vitamin D-insufficient; the proportion of insufficiency was 65% in the winter and 40% at the end of the summer. During both seasons, girls had lower vitamin D levels than did boys; those who followed the dress code of covered head, arms, and legs had the lowest levels. Students in the mid-SES school had lower 25-hydroxyvitamin D (25-OHD) levels than did the ones from the high-SES school. After adjusting for confounders, gender, SES, and body mass index remained the significant predictors of vitamin D levels in both seasons (R(2) = 0.53, for spring and 0.28 for fall). There was a significant inverse correlation between 25-OHD levels and parathyroid hormone levels that was best fitted by a curvilinear model (R(2) = 0.19).


CONCLUSIONS
Even in a sunny country, hypovitaminosis D is common in schoolchildren, more so in the winter. Girls, especially those with a lower SES, are at particular risk. The inverse changes in parathyroid hormone suggest that insufficient vitamin D levels may deleteriously affect skeletal metabolism in healthy adolescents. Vitamin D insufficiency may be prevalent in many other countries where supplementation of milk with vitamin D is not mandatory. Our results call to a reconsideration of vitamin D supplementation in high-risk adolescents to further optimize skeletal health. vitamin D insufficiency, bone metabolism, nutrition, gender, socioeconomic status.
El-Hajj  Fuleihan
G
G
Department of Internal Medicine, Endocrine Division, Calcium Metabolism and Osteoporosis Program, American University of Beirut, Beirut, Lebanon. gf01@aub.edu.lb
Nabulsi
M
M
Choucair
M
M
Salamoun
M
M
Hajj Shahine
C
C
Kizirian
A
A
Tannous
R
R
D000293:Adolescent; D000367:Age Factors; D002648:Child; D005260:Female; D006801:Humans; D007861:Lebanon / Q000453:epidemiology; D008297:Male; D012621:Seasons; D013334:Students / Q000706:statistics & numerical data*; D014808:Vitamin D Deficiency / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology*