Abstract Background Vitamin D (Vit D) deficiency is one of the major nutritional deficiencies in children. Obesity has inverse association with vitamin D levels. The aim of this study was to determine the differences in response to conventional treatment for Vit D deficiency and insufficiency in obese and normal weight children and adolescents. Materials and Methods: This nested case control study was conducted in 69 obese children and 133 normal weight matched control suffering from Vit D insufficiency or deficiency. Vit D deficiency was defined as serum 25(OH) D3 0.05). After follow up, mean Vit D level became 29.6 ng/mL in obese and 33 ng/mL in normal weight children (P<0.05). 39.8% of normal weight group still had Vit D insufficiency, while 50.7% of obese group had Vit D insufficiency or deficiency and the difference was borderline significant (P= 0.064). Conclusion Therapeutic response in obese children was less than normal weight children. It seems that treatment with higher doses of Vit D or longer period is necessary in obese children of the present study. Key Words: Adolescents, Children, Obesity, Vitamin D deficiency. *Please cite this article as: Saffari F, Shahroodi P, Oveisi S, Esmailzadehha N, Hajmanoochehri F, Jalilolghadr Sh, et al. Differences in Response to Conventional Vitamin D Therapy among Obese and Normal Weight Children and Adolescents in Qazvin, Iran. Int J Pediatr 2017; 5(9): 5725-32. DOI: 10.22038/ijp.2017.22473.188
