ESPE Abstracts

Background: Cyclic treatment with bisphosphonates (BP) is now considered a ‘standard care’ for children with osteogenesis imperfecta (OI). Vitamin D is a necessary nutrient for bone health for all children but especially for those with OI. In the literature few studies have considered the relationship between bone mineral density, vitamin D and pubertal stage in children treated with BP for OI.

Objective and hypotheses: The purpose of this study is to evaluate the vitamin D status and to asses the relationship between 25-hydroxyvitamin D (25OH-D) level, pubertal stage and the variation in lumbar spine areal bone mineral density (LS-aBMD) measurements during a 2-year follow-up in children with OI.

Method: This retrospective study comprised 28 patients affected by OI treated with neridronate for at least 4 years. Charts of these 25 patients were reviewed for mean 25OH-D level and mean variation in LS-aBMD (%ΔBMD) in 2-years follow-up. The patient cohort was divided into three groups according to pubertal stage: prepubertal group (SP1), pubertal group (SP2) and postpubertal group (SP3). Each group was divided into two subgroups numerically similar according to 25OH-D serum concentrations (A:>26 ng/ml; B:<26 ng/ml).

Results: Almost 60% of our patients have insufficient (<30 ng/ml) or deficient (<20 ng/ml) level of 25OH-D. The mean serum 25OH-D concentrations was 28.9 ng/ml (SP1 35.58±15.48 ng/ml; SP2 25.24±5.62 ng/ml; SP3 25.9±8.81 ng/ml). In prepubertal SP1 and postpubertal SP3 subgroups BMD improved, but not significantly, during the 2-years follow-up (%ΔBMD SP1 A:18%, B:14%, P:0.271; %ΔBMD SP3 A:5%, B:6.93%, P:0.322). In pubertal subgroup SP2%ΔBMD increased more in patients of subgroup A respect patients of subgroup B, with a significantly difference between the two subgroups (%ΔBMD SP2 A: 27.72%, B:11.84%, P:0.029).

Conclusion: We find a positive association between high vitamin D status and LS-aBMD in pubertal patients with OI.Stable vitamine D level above 30 ng/ml during pubertal development may keep low PTH level decreasing bone resorption and potently stimulate the increase of bone mass during treatment with BP in adolescents with OI.