Bone Abstracts

Turner syndrome (TS) is known to be associated with increased risk of osteoporosis and fracture. Childhood treatment with GH has been considered standard of care for treatment of growth failure in TS, while the influence of GH on bone health has been poorly understood. The purpose of this study is to assess the influence of GH on bone microarchitecture on a cohort of TS subjects.

TS subjects aged 16–45 were included. Bone mineral density (BMD) was assessed at the lumbar spine, hip and radius using dual-energy X-ray absorptiometry (DXA). High resolution peripheral quantitative computed tomography (HR-pQCT) scans of the radius and tibia were completed. Bone microarchitecture analysis included total volumetric BMD (Tt.BMD), cortical BMD (Ct.BMD), trabecular BMD (Tb.BMD), total area (Tt.Ar) and cortical thickness (Ct.Th). Simulated bone strength was determined using finite element (FE) analysis. Group means were compared using independent t-tests and two-way ANOVA.

Sixteen TS subjects were recruited, six GH-treated and ten non-GH-treated. Both groups were similar in regards to age, estrogen exposure and bone health related lifestyle parameters. GH-treated subjects were significantly taller than the untreated group (152.0± 3.3 vs 143.9± 6.5 cm respectively, P=0.005). DXA BMD of hip, spine and radius was similar between treatment groups. At the radius, Tt.Ar was greater among GH-treated subjects (+17.3%, P<0.03), while Tt.BMD, Ct.BMD, Tb.BMD, and Ct.Th were similar in both groups. Similarly, at the tibia, Tt.Ar was greater among the GH-treated subjects (+21.8%, P<0.005) while the remaining parameters were not significantly different. FE determined bone strength trended higher in the GH-treated group (radius +2.5%, P=0.9; tibia +6.3%, P=0.5), but results were not statistically different.

Despite GH treatment in TS resulting in increased height and larger bones, no significant difference in DXA derived BMD, HR-pQCT micro-architectural parameters, or FE simulated bone strength were detected. While these early findings may be due to insufficient statistical power, the significant difference in final height and bone area suggest a substantial GH effect on other aspects of bone growth. Further study seeks to understand the effects of GH on bone health in this unique patient population.