Bone Abstracts

Introduction: Acromegaly is a rare disease caused by excess growth hormone (GH) production by an adenoma of the anterior pituitary gland. The skeletal complications of GH and IGF-1 excess include increased bone turnover, increased cortical bone mass and deteriorated microarchitecture of trabecular bone, associated with a high risk of vertebral fractures in the presence of a relatively normal Bone Mineral Density (BMD). There are no data on bone material properties in patients with acromegaly.

Objective: To evaluate bone material properties in patients with acromegaly using Reference Point Indentation (RPI).

Methods: Cross-sectional study in 32 well-controlled acromegaly patients aged ≥18 years compared to 32 age-and fracture-matched controls. Bone Material Strength index(BMSi) was measured by RPI using the Osteoprobe. Two independent operators assessed vertebral fractures using the semi-quantitative method of Genant.

Results: Mean age of acromegaly patients (53% male) was 56.6 years (range 37.9–76.5), and 56.4 years (range 35.2–77.2) in controls (41% male). Patients with acromegaly had higher BMI (28.2 kg/m²±0.9 vs 24.0 kg/m²±0.6, P<0.001) and higher BMD at lumbar spine (1.06 g/cm²±0.20 vs. 0.92 g/cm²±0.17, P=0.006) and femoral neck (0.85 g/cm²±0.15 vs. 0.73 g/cm²±0.11, P<0.001) than controls. However, adjusted for BMI, LS BMD was not significantly different between acromegaly patients and controls.

BMSi was significantly lower in acromegaly patients than in controls (79.9±0.8 vs. 83.5±0.8, P=0.004). There was no difference in BMSi values between acromegaly patients with (n=13) or without (n=19) vertebral fractures (79.3±1.3 vs. 79.1±1.1, P=0.931), nor was there a relation between morphometric vertebral fractures and BMSi in the control group.

Conclusion: Patients with acromegaly have significantly lower Bone Material Strength index compared to controls. Furthermore, BMSi was comparable in acromegaly patients, with or without vertebral fractures. Our findings suggest that material properties of bone are impaired in patients with acromegaly and suggest that other measures than BMD should be considered to evaluate bone fragility in acromegaly.