Vitamin D deficiency in children and adolescents

Vitamin D deficiency is an important health problem in both developed and developing countries. Recent reports on the extraskeletal effects of vitamin D have led to increased interest in prevalence studies on states of deficiency/insufficiency of vitamin D. The aim of this study was to determine the frequency of vitamin D deficiency and insufficiency in children and adolescents residing in Ankara, Turkey and to investigate the factors associated with low vitamin D status.

A total of 440 children and adolescents aged between 0 and 16 years were enrolled in this study. The subjects were divided into three groups according to their vitamin D status (deficiency ≤15 ng/mL; insufficiency: 15-20 ng/mL; sufficiency ≥20 ng/mL) and also according to their age (preschool<5 years; middle childhood: 5-10 years; adolescence: 11-16 years).

Overall, 40% of the subjects were found to have 25 hydroxy vitamin D [25(OH)D] levels of less than 20 ng/mL. The levels indicated a deficiency state in 110 subjects (25%) and insufficiency - in 66 (15%). The rate of vitamin D deficiency was higher in girls, regardless of age. 25(OH)D levels correlated negatively with age (r=-0.48, p<0.001), body mass index (BMI) (r=-0.20, p=0.001) and intact parathyroid hormone (iPTH) level (r=-0.31, p=0.001). A positive correlation was observed between 25(OH)D and serum ferritin levels (r=0.15, p=0.004).

The high frequency of vitamin D deficiency in childhood (especially among adolescent girls) indicates a need for supplementation and nutritional support.