Bone Abstracts

Objectives: Vitamin D is an essential hormone for growth and development of bones in children. Prevalence of vitamin D deficiency is remarkable during childhood and adolescence throughout the world. The aim of this study was to specify the optimal dose of vitamin D in growing girls during an academic year in a sunny city.

Materials and methods: This randomized clinical trial study was carried out in Yazd in the Center of Iran in 2007; 120 junior high school girls (aged 12–15 years) were randomly divided into four groups. Sixty students in groups I and II were initially treated for vitamin D deficiency with 300 000 IU vitamin D3 and then randomly received 50 000 U/monthly or 100 000 IU/3 months vitamin D3; 60 other students in groups III and IV received 50 000 and 100 000/3 months from the beginning of the academic year. Medication continued for the entire academic year; 1 month after the last dose, serum 25(OH)D levels were measured.

Results: The mean level of 25 (OH) D was 29.7±4.60 ng/ml in group I and 30±5.61 ng/ml in group II. Mean serum levels of 25(OH)D were 15.2±6 and 23±6.8 ng/ml for groups III and IV respectively (Table 1).

Conclusion: This study shows that in the area with high prevalence of vitamin D deficiency (more than 50%), recommended doses of neither 400 nor 800 IU/day are sufficient to maintain optimal level in all. But after treatment of deficiency with 300 000 IU of vitamin D, both doses of 1000 or 2000 IU/day would maintain serum 25(OH)D concentrations ≥20 ng/ml in all of the samples during academic years. Yazd is one the sunniest provinces in the country and the Middle East, therefore this study could reveal the minimum requirement of vitamin D in other areas with less sunshine than our region.