Bone microarchitecture and estimated bone strength in men with active acromegaly

Context

Both acromegaly and adult growth hormone deficiency (GHD) are associated with increased fracture risk. Sufficient data are lacking regarding cortical bone microarchitecture and bone strength, as assessed by microfinite element analysis (µFEA).

Objective

To elucidate both cortical and trabecular bone microarchitecture and estimated bone strength in men with active acromegaly or GHD compared to healthy controls.

Design and subjects

Cross-sectional study at a clinical research center, including 48 men (16 with acromegaly, 16 with GHD and 16 healthy controls).

Outcome measures

Areal bone mineral density (aBMD), cortical and trabecular bone microarchitecture and estimated bone strength (µFEA) at the radius and tibia.

Results

aBMD was not different between the 3 groups at any skeletal site. At the radius, patients with acromegaly had greater cortical area (P < 0.0001), cortical thickness (P = 0.0038), cortical pore volume (P < 0.0001) and cortical porosity (P = 0.0008), but lower trabecular bone density (P = 0.0010) compared to controls. At the tibia, patients with acromegaly had lower trabecular bone density (P = 0.0082), but no differences in cortical bone microstructure. Compressive strength and failure load did not significantly differ between groups. These findings persisted after excluding patients with hypogonadism. Bone microarchitecture was not deficient in patients with GHD.

Conclusions

Both cortical and trabecular microarchitecture are altered in men with acromegaly. Our data indicate that GH excess is associated with distinct effects in cortical vs trabecular bone compartments. Our observations also affirm the limitations of aBMD testing in the evaluation of patients with acromegaly.

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