Endocrine Abstracts

Introduction: Osteogenesis Imperfecta (O.I.) is a genetic disorder commonly known as brittle bone disease. The majority of people with O.I. have a mutation in one of two genes, COL 1A1 or COL 1A2, that encode type I collagen. In most families, O.I. is inherited in an autosomal dominant pattern. Dual Energy X-ray Absorptiometry - bone mineral density (DXA-BMD) test provides information about bone quantity, not quality. The bisphosphonates - treatment can minimizing fractures by increasing bone density and reducing bone fragility.

Objectives: We followed the goal of BMD and the new fractures under the treatment with oral bisphosphonates, lengthways two years in six teen-agers affected by O.I. type IA.

Materials and methods: Two boys and four girls were treated with risedronate (Actonel) 35 mg/weekly, two years or more. The mean age for girls was 15.5 years and for boys 17.7 years at the debut of treatment. The boys were brothers and the girls sisters two by twos. All patients had more than four fractures in the past. At the beginning of the therapy and each 12 months the lumbar spine and whole body BMD were measured by DXA (Hologic - Delphi W; SN 7044990).

Results: At baseline the lumbar spine BMD - mean for boys was 0.782 g/cm² and increased at 0.959 g/cm² (+22.6%) after 24 months. For the girls, mean BMD lumbar spine the baseline was 0.670 g/cm² and increased at 0.751 g/cm² (+12.0%) after 24 months. The whole body BMD mean was 0.882 g/cm² before the treatment and increased at 1.105 g/cm² (+34.4%) after 24 months for boys. For girls the whole body mean BMD was for the beginning 0.782 g/cm² and increased at 0.872 g/cm² (+11.5%) at 24 months. No new fractures under the treatment.

Conclusions: The BMD remain lower than normal in O.I., even under the treatment. In our study the goal of BMD under bisphosphonates was significantly in the both sites. Oral bisphosphonates in standard doses seems to be effective therapy in patients with O.I.