Background and aims Osteogenesis imperfecta (OI) is a disorder that leads to fragile bones and significant morbidity. The aim was to find out the prevalence of Vitamin D deficiency in children with OI.

Methods In present study, 15 children with clinically severe OI on zoledronate therapy were studied. The biochemical parameters tested were Vit D level and urine DPD level along with the routine parameters like Ca, Po, ALP, and urinary calcium creatinine ratio. We used a cut-off value of 30 ng/ml for vitamin D deficiency. Also cost effectiveness of zolendronate therapy was assessed.

Results Most of the OI patients were vit D deficient (80%). The mean value of vitamin D in the study was 21.89 ± 9.76 (mean±SD), and median value was 25.49 units. This treatment in present study did not significantly increase the financial burden on the family using alternate brand of zolendronate.

Conclusions High prevalence od Vitamin D deficiency in OI may be due to their less mobility and thus less sun exposure, the low vit D level can decrease their response to zolendronate treatment Vitamin D supplementation may be needed at higher doses along with oral calcium in patients with OI put on bisphosphonates therapy. Generic preparations of zoledronate do not increase the burden of therapy in patients with OI. Further studies are needed to find out long term side effects of zoledronate therapy in children.