Effects of Vitamin D Status on DEXA Femoral Neck BMD in Children and Adolescents

Summary Vitamin D deficiency is a well-established risk factor for femoral neck fracture in the elderly. Furthermore, the antecedents to the development of osteoporosis in later life typically occur across the lifespan. Lifestyle factors leading to decreased direct sun exposure together with increased skin pigmentation, are major risk factors for vitamin D deficiency.

Project Details

At Sunshine Hospital we have previously shown that 82% of children and adolescents presenting with fracture, had clinical risk factors for vitamin D deficiency and half of these were shown to have a 25 hydroxyvitamin Dless than 50nmol/l at the end of summer. Anecdotally we have also found that DEXA femoral neck BMD, in a small number of children and adolescents presenting with fracture and vitamin D deficiency, have demonstrated relative regional low BMD at the femoral neck. To date there is no robust data in this demographic to show increasedfracture risk with mild to moderate vitamin D deficiency. Initially, a retrospective study will be conducted utilising the Western Health orthopaedic database to search for femoral neck fractures which have occurred in 6 – 18 year olds over the last 2 years. Results of femoral neck DEXA BMD performed on Sunshine Hospital Hologic machine will be retrieved for those who have had this performed, and will be assessed in those who have fractured but not had a DEXA BMD performed at the time of fracture.

A prospective study will then be conducted in the same age group, who present with fracture,and femoral neck DEXA BMD of those who are vitamin D sufficient (25 OH vitamin D greater than 75nmol/l) will be compared with those who are vitamin D deficient (25 OH vitamin D less than 50 nmol/l). Fracture sites and degree of trauma using modified Land in criteria and fracture healing rates will also be compared. It is expected that this study will demonstrate that mild to moderate vitamin D deficiency, without evidence of rickets,contributes to the development of low bone density in children and adolescence, and may possibily contribute to long term osteoporotic hip fracture in later life.