GH in combination with bisphosphonate treatment in osteogenesis imperfecta

Objective: To verify the effects of bisphosphonates (Bps) in combination with recombinant human growth hormone (rGH) in pediatric osteogenesis imperfecta (OI) patients; we focused on possible improvement of bone mineral density (BMD), projected bone areas, growth velocity and fractures risk. Design: A randomized controlled 1-year clinical trial on 30 pre-pubertal children (M:F=14:16) affected by OI (type I, IV, III) being treated with Neridronate (N). Methods: Following an observational period of 12 months during ongoing N treatment, the patients were randomly divided into two groups: 15 were treated for 12 months with rGH and N (Group Bp+rGH) and 15 continued N alone (Group Bp). We evaluated auxological parameters, number of fractures, bone age (BA), bone metabolic parameters and bone mass measurements (at lumbar spine and radius by DXA). Results: The mean variation in percentage of BMD (Delta%BMD) - at lumbar spine (L2-L4), at distal and ultra distal radius- and the projected area of lumbar spine increased significantly in Group Bp+rGH (p<0.05). Growth velocity was significantly higher during rGH treatment in group Bp+rGH vs group Bp and vs pre-treatment (p< 0.05), with no difference in increase in BA or fracture risk rate. Patients with quantitative collagen synthesis defects had a higher, although not significant, response to rGH in terms of growth velocity and BMD. Conclusions: In OI patients the combined rGH-Bp treatment may give better results than Bp treatment alone, in terms of BMD, lumbar spine projected area and growth velocity, particularly in patients with quantitative defects.