SUN-455 Abnormalities in Bone Microarchitecture of Women with Active Acromegaly Using HR-pQCT

Acromegaly has been associated with high bone turnover rate and frequency of vertebral fractures, findings mainly observed in patients with active disease and untreated hypogonadism. However, DXA measurements of bone mineral density (BMD) in acromegaly are controversial, and may be normal, low or even high when compared with normal controls. Therefore, the use of alternative diagnostic tools that evaluate bone quality, such as HR-pQCT, as well as the selection of a population of patients without risk factors for osteoporosis can improve the assessment of excess GH on bone microarchitecture. To evaluate BMD and bone microarchitecture in women with acromegaly in comparison with healthy subjects, we conducted a cross-sectional study, including twenty six women with acromegaly (11 active/15 controlled) with sixty female healthy controls matched by age and body mass index (BMI kg/m2). Areal BMD (aBMD) was measured at lumbar spine(L1-L4), femoral neck and total hip by DXA. Bone microarchitecture was assessed by HR-pQCT at the distal radius and tíbia. We enrolled twenty six women with acromegaly (40.3± 5.8years,30.2 kg/m2) and 60 control subjects (40.6 ± 5.8 years, 28.4 ± 4.6 kg/m2), none of whom had hypopituitarism. Acromegaly patients and controls were comparable for age (40.3 ± 5.8 vs 40.5 ± 5.8 years; P=0.83); and BMI (28.3 ± 5.0 vs 28.3 ± 4.6 kg/m2; P=0.12). Patients with active acromegaly showed higher IGF-1 levels than controlled patients (375.2 ± 122.6 vs 160.7 ± 44.8 ng/mL, respectively). Compared to healthy controls,patients with acromegaly showed significantly higher aBMD at lumbar L1-L4 (1.000 ± 0.11 vs 1.130 ± 0.11; P<0.01), total Hip (0.93 ± 0.11 vs 1.040 ± 0.15; P<0.001) and femoral neck (0.82 ± 0.12 vs 0.900 ± 0.16; P=0.01.). HR-pQCT at the radius, showed significantly reduced trabecular BMD (TbBMD); (P<0.01); trabecular number (TbN); (P<0.001) and increased trabecular separation (TbSp) (P<0.001). On the other hand, patients with acromegaly had increased cortical BDM(Ct.BMD); (P<0,001) and cortical thickness (CtTh); (P<0.001). At the tibia, only trabecular thickness was significantly decreased (P<0.01). No differences in BMD and bone microstructure were observed between patients with active and controlled acromegaly. Conclusions: The current study demonstrates that women with acromegaly without associated hormonal deficiencies had reduced trabecular bone microarchitecture parameters and increased cortical parameters at peripheral sites using HR-pQCT. This finding provides additional evidence for the role of GH/IGF-1 levels in establishing and regulating skeletal microstructure. The limitations of this study include the cross-sectional design and relatively small numbers of patients. Longitudinal studies are needed to confirm our findings. Funding: This work was supported by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) #2016/23765-0