Subclinical Vitamin D Insufficiency in Korean School-aged Children

Purpose: Recently, vitamin D insufficiency has increased and has been correlated to growth and puberty in children. This study was conducted to find the prevalence of subclinical vitamin D insufficiency and its influence on school-aged children in Korea.

Methods: The subjects of this study were 397 children aged 7 to 15 years who had been tested for 25-OH vitamin D3 among the outpatients of the Department of Pediatrics in Eulji General Hospital from March 2007 to February 2011. Data for age, sex, comorbidities, serum 25-OH vitamin D3, height, weight, body mass index (BMI), and sunlight exposure time were collected before and after 3 months of vitamin D administration, retrospectively.

Results: Vitamin D insufficiency was present in 343 (86%) of the subjects. In the vitamin D insufficient group, chronological age was 8.96±1.72 years, mean height (z-score [z]) was 0.51±1.26, mean BMI (z) was 0.81±2.20, and bone age was 10.26±1.75 years. In the vitamin D sufficient group, chronological age was 9.61±1.77 years, mean height (z) was-0.66±0.98, mean BMI (z) was-0.01±1.16, and bone age was 9.44±2.12 years. A paired t-test showed that three months after vitamin D administration, the mean 25-OH vitamin D3 level in the insufficient group increased to 24.38 ±10.03 ng/mL and mean BMI (z) decreased to 0.67±1.06.

Conclusion: In Korean school-aged children, vitamin D insufficiency were relatively higher and may be closely related with higher BMI. Insufficient rise of the level of vitamin D after supplementation suggest the new supplementation guidelines, especially for Korean children.