Association of 25-hydroxy Vitamin D levels with indexes of general and abdominal obesity in Iranian adolescents: The CASPIAN-III study

Background: This study aimed to determine the association of serum 25-hydroxy Vitamin D (25(OH) D) levels with measures of general and abdominal obesity in Iranian adolescents. Materials and Methods: This nationwide cross-sectional study was conducted among 1090 students, aged 10-18 years, living in 27 provinces in Iran. Serum concentration of 25(OH) D was analyzed quantitatively by direct competitive immunoassay chemiluminescence method. Body mass index (BMI) and waist-to-height ratio (WHtR) were considered as measures of generalized and abdominal obesity, respectively. Results: Study participants consisted of 1090 adolescents (51.9% boy and 67.1% urban residents) with mean age, BMI, and waist circumference of 14.7 (2.6) years, 19.3 (4.2) kg/m(2), and 67.82 (12.23) cm, respectively. The median serum 25(OH) D was 13.0 ng/mL (interquartile range: 20.6). Overall, 40% of participants were Vitamin D deficient, and 39% were Vitamin D insufficient. Serum 25(OH) D level was not associated with BMI and WHtR. Conclusion: We did not document any significant association between serum 25(OH) D level and anthropometric measures in adolescents. This finding may be because of considerably high prevalence of hypovitaminosis D in the study population.