Evaluation of Vitamin D Status and Bone Mineral Density in Preschool Children with Fractures

Abstract

Vitamin D is essential for calcium homeostasis and bone mineralization during childhood. However, the effectiveness of vitamin D supplementation in improving bone health and reducing fracture risk in children remains controversial. This study aimed to assess serum 25-hydroxyvitamin D [25(OH)D], vitamin D–binding protein (DBP), and calcium levels, as well as bone mineral density (BMD) in preschool children with fractures and evaluate the short-term effects of vitamin D supplementation. This cross-sectional study included 90 children aged 3–5 years, divided into the fracture (n=45) and control (n=45) groups. Serum 25(OH)D, calcium, and DBP levels were measured. BMD was assessed using dual-energy X-ray absorptiometry at the lumbar spine and femoral neck. Children in the fracture group received vitamin D₃ supplementation (600 IU/day) for 2 months, followed by reassessment. Statistical analyses included group comparisons, correlation, and regression models. Children with fractures had significantly lower serum 25(OH)D, calcium, and DBP levels compared to controls (p<0.001). No baseline differences in BMD were observed between groups. After supplementation, serum biomarkers and femoral neck BMD significantly improved (p<0.001), while lumbar spine BMD showed a significant but paradoxical decrease. Serum 25(OH)D, DBP, and lumbar spine Z-score were independent predictors of femoral neck BMD. Moreover, higher vitamin D levels and BMD were independently associated with a reduced fracture risk. Our findings demonstrated that vitamin D deficiency was strongly associated with fractures in preschool children, while supplementation improved biochemical markers and site-specific BMD. Thus, vitamin D status presents a key determinant of bone health and fracture risk in children.