IMPE Abstracts

Background: Osteogenesis imperfecta (OI) is a genetic connective tissue disorder with variable phenotype, mainly characterized by bone fragility, multiple fractures, bone deformities, short stature and non-skeleton findings like blue/gray scleras. The pharmacological approach for OI is based on the use of bisphosphonates to improve bone health. Since growth failure is a predominant feature of OI, recombinant human growth hormone (rhGH) treatment has been suggested as a potential intervention, especially for mild forms.

Case Report: We describe a 14-year-old boy diagnosed with OI type I, born at term and appropriate for gestational age, whose mother is affected by OI. His first fracture occurred at 1 year and 2 months of age, and 3 other fractures before treatment with pamidronate at 2 years and 9 months of age. He has gray sclera, slightly valgus knees, mild spinal deformity and excavated thorax. Height Z-score (H-SDS) before bisphosphonate was -0.49 (2 years and 9 months old). The target height Z-score was -0.76. At 8-years-old his bone age (BA) was compatible with his chronological age (CA) and endocrine work up showed: growth hormone peak of 9.03ng/mL after clonidine stimulation and normal IGF-1 concentration. At 8 years and 9 months, rhGH therapy was started (0.043mg/kg/day) and his H-SDS was -1.66; One and a half year later he suffered an elbow fracture playing football. Puberty started at 12 years old, when his H-SDS was -0,20 and BA was equivalent to CA. At his last visit he was 14 years and 2 months, H-SDS was +0.04, Tanner pubertal development was P4 G4 and his BA was compatible with his CA. At age 13 his bone mineral density Z-score was +2.2 (total body less head) and +1.6 (lumbar spine), evaluated by dual energy X-ray absorptiometry.

Conclusion: rhGH has been proposed as an intervention for mild forms of OI to improve growth rate, with conflicting results on fracture rate and bone mineral density. Some studies have suggested positive effects of rHGH treatment on height, however its use is not universally accepted. We present the case of a 14 years old boy, treated with rHGH, with positive results on growth and no negative influence on fracture rate.